Highly Dispersed Platinum Chlorine Atoms Anchored on Gold Quantum Dots for a Highly Efficient Electrocatalyst

Growing highly ordered Pt and Mn bimetallic single atomic layers over graphdiyne

Controlling the precise growth of atoms is necessary to achieve manipulation of atomic composition and atomic position, regulation of electronic structure, and an understanding of reactions at the atomic level. Herein, we report a facile method for ordered anchoring of zero-valent platinum and manganese atoms with single-atom thickness on graphdiyne under mild conditions. Due to strong and incomplete charge transfer between graphdiyne and metal atoms, the formation of metal clusters and nanoparticles can be inhibited. The size, composition and structure of the bimetallic nanoplates are precisely controlled by the natural structure-limiting effect of graphdiyne. Experimental characterization clearly demonstrates such a fine control process. Electrochemical measurements show that the active site of platinum-manganese interface on graphdiyne guarantees the high catalytic activity and selectivity (~100%) for alkene-to-diol conversion. This work lays a solid foundation for obtaining high-performance nanomaterials by the atomic engineering of active site.

Direct conversion of CO2 to CH4 on Pd/graphdiyne single-crystalline

A major impediment to the development of the efficient use of artificial photosynthesis is the lack of highly selective and efficient photocatalysts toward the conversion of CO2 by sunlight energy at room temperature and ambient pressure. After many years of hard work, we finally completed the synthesis of graphdiyne-based palladium quantum dot catalysts containing high-density metal atom steps for selective artificial photosynthesis. The well-designed interface structure of the catalyst is composed of electron-donor and acceptor groups, resulting in the obvious incomplete charge-transfer phenomenon between graphdiyne and plasmonic metal nanostructures on the interface. These intrinsic characteristics are the origin of the high performance of the catalyst. Studies on its mechanism reveal that the synergism between 'hot electron' from local surface plasmon resonance and rapid photogenerated carrier separation at the ohmic contact interface accelerates the multi-electron reaction kinetics. The catalyst can selectively synthesize CH4 directly from CO2 and H2O with selectivity of near 100% at room temperature and pressure, and exhibits transformative performance, with an average CH4 yield of 26.2 μmol g-1 h-1 and remarkable long-term stability.

Controlled Growth Lateral/Vertical Heterostructure Interface for Lithium Storage

Artificial heterostructures with structural advancements and customizable electronic interfaces are fundamental for achieving high-performance lithium-ion batteries (LIBs). Here, a design idea for a covalently bonded lateral/vertical black phosphorus (BP)-graphdiyne oxide (GDYO) heterostructure achieved through a facile ball-milling approach, is designed. Lateral heterogeneity is realized by the sp2-hybridized mode P-C bonds, which connect the phosphorus atoms at the edges of BP with the carbon atoms of the terminal acetylene in GDYO. The vertical connection of the heterojunction of BP and GDYO is connected by P-O-C bond. Experimental and theoretical studies demonstrate that BP-GDYO incorporates interfacial and structural engineering features, including built-in electric fields, chemical bond interactions, and maximized nanospace confinement effects. Therefore, BP-GDYO exhibits improved electrochemical kinetics and enhanced structural stability. Moreover, through ex- and in-situ studies, the lithiation mechanism of BP-GDYO, highlighting that the introduction of GDYO inhibits the shuttle/dissolution effect of phosphorus intermediates, hinders volume expansion, provides more reactive sites, and ultimately promotes reversible lithium storage, is clarified. The BP-GDYO anode exhibits lithium storage performance with high-rate capacity and long-cycle stability (602.6 mAh g-1 after 1 000 cycles at 2.0 A g-1). The proposed interfacial and structural engineering is universal and represents a conceptual advance in building high-performance LIBs electrode.

Tailoring Interfacial Electric Field by Gold Nanoparticles Enable Electrocatalytic Lithium Polysulfides Conversion for Lithium-Sulfur Batteries

Although lithium-sulfur batteries (LSBs) are considered as the promising next rechargeable storage system ascribing to their decent specific capacity of inorganic sulfur, the development is partially impeded by inferior electronic conductivity, severe shuttle effect, and large volume variation. To tackle the issues above, a great deal of effort is made on sulfur-containing polymer (SCP) that shows better electrochemical performance. Nevertheless, sluggish conversion of lithium polysulfides (LiPSs) obstructs battery performance yet. Herein, electrocatalytic LiPSs with full conversion by tailoring the interfacial electric field are discovered based on gold nanoparticles (AuNPs) anchored on sulfurized polyaniline (SPANI). A downhill path of Gibbs free energy from organosulfur polymer to intermediate product means more spontaneously and favorable for full conversion, as the significant enhancement of electron density of state in the vicinity of the HOMO level for the AuNPs increase the electron transition probability rate. This composite delivers satisfactory electrochemical performance, especially increased rate capacity of >300 mAh g-1. Furthermore, catalyst mechanism on molecule level is proposed that AuNPsdominate chemical enhancement and higher electron delocalizablility betweenAuNPs and LiPSs molecules. These results can erect a promising strategy for enhancing lithium polysulfides full conversion.

The Accurate Synthesis of a Multiscale Metallic Interface on Graphdiyne

The accurate construction of composite material systems containing graphdiyne (GDY) and other metallic materials has promoted the formation of innovative structures and practical applications in the fields of energy, catalysis, optoelectronics, and biomedicine. To fulfill the practical requirements, the precise formation of multiscale interfaces over a wide range, from single atoms to nanostructures, plays an important role in the optimization of the structural design and properties. The intrinsic correlations between the structure, synthesis process, characteristic properties, and device performance are systematically investigated. This review outlines the current research achievements regarding the controlled formation of multiscale metallic interfaces on GDY. Synthetic strategies for interface regulation, as well as the correlation between the structure and performance, are presented. Furthermore, innovative research ideas for the design and synthesis of functional metal-based materials loaded onto GDY-based substances are also provided, demonstrating the promising application potential of GDY-based materials.

Theoretical Prediction Leads to Synthesize GDY Supported InOx Quantum Dots for CO2 Reduction

The preparation of formic acid by direct reduction of carbon dioxide is an important basis for the future chemical industry and is of great significance. Due to the serious shortage of highly active and selective electrocatalysts leading to the development of direct reduction of carbon dioxide is limited. Herein the target catalysts with high CO2RR activity and selectivity were identified by integrating DFT calculations and high-throughput screening and by using graphdiyne (GDY) supported metal oxides quantum dots (QDs) as the ideal model. It is theoretically predicted that GDY supported indium oxide QDs (i.e., InOx/GDY) is a new heterostructure electrocatalyst candidate with optimal CO2RR performance. The interfacial electronic strong interactions effectively regulate the surface charge distribution of QDs and affect the adsorption/desorption behavior of HCOO* intermediate during CO2RR to achieve highly efficient CO2 conversion. Based on the predicted composition and structure, we synthesized the advanced catalytic system, and demonstrates superior CO2-to-HCOOH conversion performance. The study presents an effective strategy for rational design of highly efficient heterostructure electrocatalysts to promote green chemical production.

Well-dispersed Pt/Nb2O5on zeolitic imidazolate framework derived nitrogen-doped carbon for efficient oxygen reduction reaction

In this work, an advanced hybrid material was constructed by incorporating niobium pentoxide (Nb2O5) nanocrystals with nitrogen-doped carbon (NC) derived from ZIF-8 dodecahedrons, serving as a support, referred to as Nb2O5/NC. Pt nanocrystals were dispersed onto Nb2O5/NC using a simple impregnation reduction method. The obtained Pt/Nb2O5/NC electrocatalyst showed high oxygen reduction reaction (ORR) activity due to three-phase mutual contacting structure with well-dispersed Pt and Nb2O5NPs. In addition, the conductive NC benefits electron transfer, while the induced Nb2O5can regulate the electronic structure of Pt element and anchor Pt nanocrystals, thereby enhancing the ORR activity and stability. The half-wave potential (E1/2) for Pt/Nb2O5/NC is 0.886 V, which is higher than that of Pt/NC (E1/2= 0.826 V). The stability examinations demonstrated that Pt/Nb2O5/NC exhibited higher electrocatalytic durability than Pt/NC. Our work provides a new direction for synthesis and structural design of precious metal/oxides hybrid electrocatalysts.

Positional Thiophene Isomerization: A Geometric Strategy for Precisely Regulating the Electronic State of Covalent Organic Frameworks to Boost Oxygen Reduction

With the oxygen conversion efficiency of metal-free carbon-based fuel cells dramatically improved, the building blocks of covalent organic frameworks (COFs) raised principal concerns on the catalytic active sites with indistinct electronic states. Herein, to address this issue, we demonstrate COFs for oxygen reduction reaction (ORR) by regulating the edge-hanging thiophene units, and the molecular geometries are further modulated via positional thiophene isomerization strategy, affording isomeric COF-α with 2-substitution and COF-β with 3-substitution on the frameworks. The electronic states and intermediate adsorption ability are well-regulated through geometric modification, resulting in controllable chemical activity and local density of π-electrons. Notably, the introduction of thiophene units with different substitution positions into a pristine pure carbon-based COF model COF-Ph achieves excellent activity with a half-wave potential of 0.76 V versus the reversible hydrogen electrode, which is higher than most of those metal-free or metal-based electrocatalysts. Utilizing the combination of theoretical prediction and in situ Raman spectra, we show that the isomeric thiophene skeleton (COF-α and COF-β) can induce the dangling unit activation, accurately identifying the pentacyclic-carbon (thiophene α-position) adjacent to sulfur atom as active sites. The results suggest that the isomeric dangling groups in COFs are suitable for the ORR with promising geometry construction.

A universal synthesis strategy of Pd-based trimetallic nanowires for efficient alcohol electrooxidation

Trimetallic nanowires (NWs) have drawn much attention in efficient alcohol oxidation reaction (AOR) due to their unique features, including high atomic utilization efficiency and fast electron transfer ability. However, a universal strategy to synthesize Pd-based trimetallic NWs with high catalytic performance is still lacking. Herein, we develop a universal method for facile synthesis of PdBiM (M = Pt, Ru, Ir, Co, Cu) NWs with excellent AOR activities. By taking PdBiPt NWs as an example, the formation mechanism was investigated, and it is found that introduction of bismuth (Bi) plays an important role in facilitating the formation of the NW structure. Moreover, the PdBiPt NWs deliver an outstanding performance toward both the ethanol oxidation reaction (EOR) and the methanol oxidation reaction (MOR). Density functional theory (DFT) calculations together with experimental results disclose that the moderate electronic structure of trimetallic PdBiPt NWs can optimize the adsorption of OHads and weaken the adsorption of COads, thereby leading to the substantially enhanced AOR performance. We believe that this work can inspire the design of multimetallic NWs as high-performance catalysts.

Electroless Deposition of Palladium Nanoparticles on Graphdiyne Boosts Electrochemiluminescence

Modulating the electronic structure of metal nanoparticles via metal-support interaction has attracted intense interest in the field of catalytic science. However, the roles of supporting substrates in regulating the catalytic properties of electrochemiluminescence (ECL) remain elusive. Here, we find that the use of graphdiyne (GDY) as the substrate for electroless deposition of Pd nanoparticles (Pd/GDY) produces the most pronounced anodic signal enhancement in luminol-dissolved oxygen (O2) ECL system as co-reactant accelerator over other carbon-based Pd composite nanomaterials. Pd/GDY exhibits electrocatalytic activity for the reduction of O2 through a four-electron pathway at approximately -0.059 V (vs Ag/AgCl) in neutral solution forming reactive oxygen species (ROS) as intermediates. The study shows that the interaction of Pd and GDY increases the amount and stability of ROS on the Pd/GDY electrode surface and promotes the reaction of ROS and luminol anion radical to generate excited luminol, which significantly boosts the luminol anodic ECL emission. Based on quenching of luminol ECL through the consumption of ROS by antioxidants, we develop a platform for the detection of intracellular antioxidants. This study provides an avenue for the development of efficient luminol ECL systems in neutral media and expands the biological application of ECL systems.

Modification Strategies for Development of 2D Material-Based Electrocatalysts for Alcohol Oxidation Reaction

2D materials, such as graphene, MXenes (metal carbides and nitrides), graphdiyne (GDY), layered double hydroxides, and black phosphorus, are widely used as electrocatalyst supports for alcohol oxidation reactions (AORs) owing to their large surface area and unique 2D charge transport channels. Furthermore, the development of highly efficient electrocatalysts for AORs via tuning the structure of 2D support materials has recently become a hot area. This article provides a critical review on modification strategies to develop 2D material-based electrocatalysts for AOR. First, the principles and influencing factors of electrocatalytic oxidation of alcohols (such as methanol and ethanol) are introduced. Second, surface molecular functionalization, heteroatom doping, and composite hybridization are deeply discussed as the modification strategies to improve 2D material catalyst supports for AORs. Finally, the challenges and perspectives of 2D material-based electrocatalysts for AORs are outlined. This review will promote further efforts in the development of electrocatalysts for AORs.

Advanced Multilayered Electrode with Planar Building Blocks Structure for High-Performance Lithium-Ion Storage

To achieve the high-performance of lithium-ion battery, the optimization of electrode materials has generally been considered as the one of the important methods. But most of those works pay attention to the new materials preparation or interface modification rather than the structural innovation. Here, an advanced electrode (GDY/BP/GDY-E) with multilevel layered architecture constructed by planar building blocks stacking structure has been designed and fabricated to explore the structure design of the electrode. This new structure is assembled by graphdiyne (GDY) and black phosphorus (BP) in parallel to form a building block (GDY/BP/GDY). The electric fields between the two GDY sides of the planar building block structure contribute to the superior migration dynamics of lithium ions and desirable pseudocapacitance behavior. Meanwhile, the planar stacking structure of GDY/BP/GDY can efficiently inhibit volume expansion of BP and a series of parasitic reactions of electrolytes during the long-term cycling. The advanced GDY/BP/GDY-E exhibits excellent high-rate performance (1418.8 mAh g-1 at 0.1 A g-1 ) and cycling stability (391.7 mAh g-1 after 5000 cycles at 10 A g-1 ). Such structural design of electrode materials shows a new way to develop high-performance electrodes.

Hydrogen co-production via nickel-gold electrocatalysis of water and formaldehyde

Hydrogen is one of the most promising future energy sources due to its highly efficient energy storage and carbon-free features. However, the energy input required for a hydrogen production protocol is an essential factor affecting its widespread adoption. Water electrolysis for hydrogen production currently serves a vital role in the industrial field, but the high overpotential of the oxygen evolution reaction (OER) dramatically impedes its practical application. The formaldehyde oxidation reaction (FOR) has emerged as a more thermodynamically favorable alternative, and the innovation of compatible electrodes may steer the direction of technological evolution. We have designed Au-Vo-NiO/CC as a catalyst that triggers the electrocatalytic oxidation of formaldehyde, efficiently producing H2 at the ultra-low potential of 0.47 V (vs. RHE) and maintaining long-term stability. Integrated with the cathodic hydrogen evolution reaction (HER), this bipolar H2 production protocol achieves a nearly 100% Faraday efficiency (FE).

Promoting electrochemical nitrogen fixation by nanoporous AuCu alloys

Electrochemical nitrogen fixation provides a sustainable alternative to the Haber-Bosch technique. Herein, nanoporous AuCu alloys are fabricated with more active sites and accessible channels, which promote N2 absorbability and activation. Our catalyst displays superior efficiency of 45.7%, ammonia yield of 25.7 μg h-1 cm-2 and selectivity of 98%, overcoming solid Au and Cu nanoparticles.

Highly Selective Electrocatalytic Olefin Hydrogenation in Aqueous Solution

Selective hydrogenation of olefins with water as the hydrogen source at ambient conditions is still a big challenge in the field of catalysis. Herein, the electrocatalytic hydrogenation of purely aliphatic and functionalized olefins was achieved by using graphdiyne based copper oxide quantum dots (Cux O/GDY) as cathodic electrodes and water as the hydrogen source, with high activity and selectivity in aqueous solution at high current density under ambient temperature and pressure. In particular, the sp-/sp2 -hybridized graphdiyne catalyst allows the selective hydrogenation of cis-trans isomeric olefins. The chemical and electronic structure of the GDY results in the incomplete charge transfer between GDY and Cu atoms to optimize the adsorption/desorption of the reaction intermediates and results in high reaction selectivity and activity for hydrogenation reactions.

Length-tunable Pd2Sn@Pt core-shell nanorods for enhanced ethanol electrooxidation with concurrent hydrogen production

The electrooxidation of ethanol as an alternative to the oxygen evolution reaction presents a promising approach for low-cost hydrogen production. However, the design and synthesis of efficient ethanol oxidation electrocatalysts remain key challenges. Here, a colloidal procedure is developed to prepare Pd2Sn@Pt core-shell nanorods with an expanded Pt lattice and tunable length. The obtained Pd2Sn@Pt catalysts exhibit superior activity and stability for ethanol electrooxidation compared to Pd2Sn and commercial Pt/C catalysts. By tuning the length of the Pd2Sn@Pt nanorods, remarkable mass activity of up to 4.75 A mgPd+Pt-1 and specific activity of 20.14 mA cm-2 are achieved for the short nanorods owing to their large specific surface area. A hybrid electrolysis system for ethanol oxidation and hydrogen evolution is constructed using Pd2Sn@Pt as the anodic catalyst and Pt mesh as the cathode. The system requires a low cell voltage of 0.59 V for the simultaneous production of acetic acid and hydrogen at a current density of 10 mA cm-2. Density functional theory calculations further reveal that the strained Pt shell reduces energy barriers in the ethanol electrooxidation pathway, facilitating the conversion of ethanol to acetic acid. This work provides valuable guidance for developing highly efficient ethanol electrooxidation catalysts for integrated hydrogen production systems.

Boosting the Methanol Oxidation Reaction Activity of Pt-Ru Clusters via Resonance Energy Transfer

The sluggish kinetics of the methanol oxidation reaction (MOR) with PtRu electrocatalyst severely hinder the commercialization of direct methanol fuel cells (DMFCs). The electronic structure of Pt is of significant importance for its catalytic activity. Herein, it is reported that low-cost fluorescent carbon dots (CDs) can regulate the behavior of the D-band center of Pt in PtRu clusters through resonance energy transfer (RET), resulting in a significant increase in the catalytic activity of the catalyst participating in methanol electrooxidation. For the first time, the bifunction of RET is used to provide unique strategy for fabrication of PtRu electrocatalysts, not only tunes the electronic structure of metals, but also provides an important role in anchoring metal clusters. Density functional theory calculations further prove that charge transfer between CDs and Pt promotes the dehydrogenation of methanol on PtRu catalysts and reduces the free energy barrier of the reaction associated with the oxidation of CO* to CO2 . This helps to improve the catalytic activity of the systems participating in MOR. The performance of the best sample is 2.76 times higher than that of commercial PtRu/C (213.0 vs 76.99 mW cm - 2 mg Pt - 1 ${\rm{mW\ cm}}^{ - 2}{\rm{\ mg}}_{{\rm{Pt}}}^{ - 1}$ ). The fabricated system can be potentially used for the efficient fabrication of DMFCs.

Fe-Ni Diatomic Sites Coupled with Pt Clusters to Boost Methanol Electrooxidation via Free Radical Relaying

Pt-based catalysts for direct methanol fuel cells (DMFCs) are still confronted with the challenge of over-oxidation of Pt and poisoning effect of intermediates; therefore, a spatial relay strategy was adopted to overcome these issues. Herein, Pt clusters were creatively fixed on the N-doped carbon matrix with rich Fe-Ni diatoms, which can provide independent reaction sites for methanol oxidation reaction (MOR) and enhance the catalytic activity due to the electronic regulation effect between Pt cluster and atomic-level metal sites. The optimized Pt/FeNi-NC catalyst shows MOR electrocatalytic activity of 2.816 A mgPt -1 , 2.6 times that of Pt/C (1.115 A mgPt -1 ). Experiments combined with DFT study reveal that Fe-Ni diatoms and Pt clusters take charge of hydroxyl radical (⋅OH) generation and methanol activation, respectively. The free radical relaying of ⋅OH could prevent the over-oxidation of Pt. Meanwhile, ⋅OH from Fe-Ni sites accelerates the elimination of intermediates, thus improving the durability of catalysts.

Ir0/graphdiyne atomic interface for selective epoxidation

The development of catalysts that can selectively and efficiently promote the alkene epoxidation at ambient temperatures and pressures is an important promising path to renewable synthesis of various chemical products. Here we report a new type of zerovalent atom catalysts comprised of zerovalent Ir atoms highly dispersed and anchored on graphdiyne (Ir⁰/GDY) wherein the Ir⁰ is stabilized by the incomplete charge transfer effect and the confined effect of GDY natural cavity. The Ir⁰/GDY can selectively and efficiently produce styrene oxides (SO) by electro-oxidizing styrene (ST) in aqueous solutions at ambient temperatures and pressures with high conversion efficiency of ∼100%, high SO selectivity of 85.5%, and high Faradaic efficiency (FE) of 55%. Experimental and density functional theory (DFT) calculation results show that the intrinsic activity and stability due to the incomplete charge transfer between Ir⁰ and GDY effectively promoted the electron exchange between the catalyst and reactant molecule, and realized the selective epoxidation of ST to SO. Studies of the reaction mechanism demonstrate that Ir⁰/GDY proceeds a distinctive pathway for highly selective and active alkene-to-epoxide conversion from the traditional processes. This work presents a new example of constructing zerovalent metal atoms within the GDY matrix toward selective electrocatalytic epoxidation.

Two-Dimensional Carbon Graphdiyne: Advances in Fundamental and Application Research

Graphdiyne (GDY), a rising star of carbon allotropes, features a two-dimensional all-carbon network with the cohybridization of sp and sp² carbon atoms and represents a trend and research direction in the development of carbon materials. The sp/sp²-hybridized structure of GDY endows it with numerous advantages and advancements in controlled growth, assembly, and performance tuning, and many studies have shown that GDY has been a key material for innovation and development in the fields of catalysis, energy, photoelectric conversion, mode conversion and transformation of electronic devices, detectors, life sciences, etc. In the past ten years, the fundamental scientific issues related to GDY have been understood, showing differences from traditional carbon materials in controlled growth, chemical and physical properties and mechanisms, and attracting extensive attention from many scientists. GDY has gradually developed into one of the frontiers of chemistry and materials science, and has entered the rapid development period, producing large numbers of fundamental and applied research achievements in the fundamental and applied research of carbon materials. For the exploration of frontier scientific concepts and phenomena in carbon science research, there is great potential to promote progress in the fields of energy, catalysis, intelligent information, optoelectronics, and life sciences. In this review, the growth, self-assembly method, aggregation structure, chemical modification, and doping of GDY are shown, and the theoretical calculation and simulation and fundamental properties of GDY are also fully introduced. In particular, the applications of GDY and its formed aggregates in catalysis, energy storage, photoelectronic, biomedicine, environmental science, life science, detectors, and material separation are introduced.

Prussian-blue-analogue derived FeNi2S4/NiS nanoframes supported by N-doped graphene for highly efficient methanol oxidation electrocatalysis

The design of effective and robust non-noble metal electrocatalysts to enhance catalytic reaction kinetic is critical to promote methanol oxidation catalysis. Herein, hierarchical Prussian blue analogue (PBA)-derived sulfide heterostructures supported by N-doped graphene (FeNi₂S₄/NiS-NG) as efficient catalysts have been developed for methanol oxidation reaction (MOR). Benefiting from the merits of hollow nanoframes structure and heterogeneous sulfide synergy, FeNi₂S₄/NiS-NG composite not only possesses abundant active sites to boost the catalytic properties but also alleviates the CO poisoning effect during the process exhibiting favorable kinetic behavior toward MOR. Specifically, the remarkable catalytic activity (97.6 mA cm^-2/1544.3 mA mg^-1) of FeNi₂S₄/NiS-NG for methanol oxidation was achieved, superior to most reported non-noble electrocatalysts. Additionally, the catalyst showed competitive electrocatalytic stability, with a current density of over 90% after 2000 consecutive CV cycles. This study offers promising insights into the rational modulation of the morphology and components of precious-metal-free catalysts for fuel cell applications.

Design, synthesis, and application of some two-dimensional materials

Two-dimensional (2D) materials are widely used as key components in the fields of energy conversion and storage, optoelectronics, catalysis, biomedicine, etc. To meet the practical needs, molecular structure design and aggregation process optimization have been systematically carried out. The intrinsic correlation between preparation methods and the characteristic properties is investigated. This review summarizes the recent research achievements of 2D materials in the aspect of molecular structure modification, aggregation regulation, characteristic properties, and device applications. The design strategies to fabricate functional 2D materials starting from precursor molecules are introduced in detail referring to organic synthetic chemistry and self-assembly technology. It provides important research ideas for the design and synthesis of related materials.

Scalable synthesis of soluble crystalline ionic-graphdiyne by controlled ion expansion

Graphdiyne (GDY) is a promising material possessing extensive electronic tunability, high π conjugacy, and ordered porosity at a molecular level for the sp/sp2-hybridized periodic structures. Despite these advantages, the preparation of soluble and crystalline graphdiyne is limited by the relatively compact stacking interactions, mostly existing in thick-layer and insoluble solids. Herein, we proposed a strategy of "framework charge-induced intercalation (FCII)" for the synthesis of a soluble (4.3 mg ml-1) and yet interlayer-expanded (∼0.6 Å) crystalline ionic graphdiyne, named as N+-GDY, through regulating the interlayer interactions. The skeleton of such a sample is positively charged, and then the negative ions migrate to the interlayer to expand the space, endowing the N+-GDY with solution processability. The crystal structure of N+-GDY is proved through analysis of HR-TEM images under different axes of observation and theoretical simulations. The resulting N+-GDY possesses high dispersity in organic solvents to produce a pure-solution phase which is conducive to the formation of oriented N+-GDY films, accompanied by exfoliation-nanosheet restacking. The film exhibits a conductivity of 0.014 S m-1, enabling its applications in electronic devices.

Single-Atom Nano-Islands (SANIs): A Robust Atomic-Nano System for Versatile Heterogeneous Catalysis Applications

Academician Tao Zhang from China and co-workers designed the first Pt₁ /FeO_x single-atom catalysts (SACs) in 2011, and they proposed the concept of "single-atom catalysis" in the field of heterogeneous catalysis. Generally, it is easy for active metal single-atom sites on a carrier to migrate and aggregate, which results in poor performance; or the chemical bond between the metal atom and carrier is too strong (immovable), which results in passivation of the active site. Recently, "nano-island" type SACs were designed, in which the active metal atoms are isolated on the "islands", and can move within the respective "island", but the migration across the "island" is blocked, to achieve a dynamic confinement design of single atoms (that is, a "moving but not aggregating" design philosophy). Herein, a new concept of "single-atom nano-islands (SANIs)" is proposed to describe these congeneric "atomic-nano" systems in heterogeneous catalysis fields. Particularly, the SANIs are divided into three categories: "one-island-one-atom", "one-island-multi-atoms", and "island-sea synergism" architectures. The scientific significance and application principles of SANIs in versatile heterogeneous catalysis fields (i.e., thermocatalysis, electrocatalysis, and photocatalysis) are summarized. The challenges and proposals of SANIs are also provided.

Subnanoscale Dual-Site Pd-Pt Layers Make PdPtCu Nanocrystals CO-Tolerant Bipolar Effective Electrocatalysts for Alcohol Fuel Cell Devices

Finding a high-performance low-Pt bipolar electrocatalyst in actual direct alcohol fuel cells (DAFCs) remains challenging and desirable. Here, we developed a crystalline PdPtCu@amorphous subnanometer Pd-Pt "dual site" layer core-shell structure for the oxygen reduction reaction (ORR) and alcohol (methanol, ethylene glycol, glycerol, and their mixtures) oxidation reaction (AOR) in an alkaline electrolyte (denoted D-PdPtCu). The prepared D-PdPtCu/C achieved a direct 4-electron ORR pathway, a full oxidation pathway for AOR, and high CO tolerance. The ORR mass activity (MA) of D-PdPtCu/C delivered a 52.8- or 59.3-fold increase over commercial Pt/C or Pd/C, respectively, and no activity loss after 20000 cycles. The D-PdPtCu/C also exhibited much higher AOR MA and stability than Pt/C or Pd/C. Density functional theory revealed the intrinsic nature of a subnanometer Pd-Pt "dual site" surface for ORR and AOR activity enhancement. The D-PdPtCu/C as an effective bipolar electrocatalyst yielded higher peak power densities than commercial Pt/C in actual DAFCs.

Ultra-high-efficiency capture of lead ions over acetylenic bond-rich graphdiyne adsorbent in aqueous solution

A satisfactory material with high adsorption capacity is urgently needed to solve the serious problem of environment and human health caused by lead pollution. Herein, hydrogen-substituted graphdiyne (HsGDY) was successfully fabricated and employed to remove lead ions from sewage and lead-containing blood. The as-prepared HsGDY exhibits the highest adsorption capacity of lead among the reported materials with a maximum adsorption capacity of 2,390 mg/g, i.e., ~five times larger than that of graphdiyne (GDY). The distinguished hexagonal hole and stack mode of HsGDY allows the adsorption of more lead via its inner side adsorption mode in one single unit space. In addition, the Pb 6s and H 1s hybridization promotes the strong bonding of lead atom adsorbed at the acetylenic bond of HsGDY, contributing to the high adsorption capacity. HsGDY can be easily regenerated by acid treatment and showed excellent regeneration ability and reliability after six adsorption-regeneration cycles. Langmuir isotherm model, pseudo second order, and density functional theory (DFT) demonstrated that the lead adsorption process in HsGDY is monolayer chemisorption. Furthermore, the HsGDY-based portable filter can handle 1,000 μg/L lead-containing aqueous solution up to 1,000 mL, which is nearly 6.67 times that of commercial activated carbon particles. And, the HsGDY shows good biocompatibility and excellent removal efficiency to 100 μg/L blood lead, which is 1.7 times higher than that of GDY. These findings suggest that HsGDY could be a promising adsorbent for practical lead and other heavy metal removal.

Synthesis of a Wheel-Shaped Nanographdiyne

Graphdiyne, a sp- and sp²-hybridized 2D π-conjugated carbon material with well-dispersed pores and unique electronic properties, was well investigated and applied in catalysis, electronics, optics, and energy storage and conversion. Graphdiyne fragments with conjugation in 2D can provide in-depth insights for understanding the intrinsic structure-property relationships of graphdiyne. Herein, an atomic precise wheel-shaped nanographdiyne composed of six dehydrobenzo [18] annulenes ([18]DBAs, the smallest macrocyclic unit of graphdiyne), was realized through the sixfold intramolecular Eglinton coupling in the hexabutadiyne precursors obtained by the sixfold Cadiot-Chodkiewicz cross-coupling of hexaethynylbenzene. Its planar structure was revealed by X-ray crystallographic analysis. The full cross-conjugation of the six 18π electron circuits yields the π-electron conjugation along the giant π core. This work provides a realizable method for the synthesis of future graphdiyne fragments with different functional groups and/or heteroatom doping, as well as the study of the unique electronic/photophysical properties and aggregation behavior of graphdiyne.

Graphdiyne aerogel architecture via a modified Hiyama coupling reaction for gas adsorption

Carbon aerogels are special porous materials with low density and large specific surface area and have advanced applications. As a new type of carbon nanomaterials, graphdiynes (GDY) aerogel possess a highly π-conjugated structure, unique sp/sp²-hybridized linkages, and well-distributed intrinsic pores, which endow GDY aerogel with great potential applications. However, the fabrication of macroscopic GDY aerogel is still an ongoing challenge due to intrinsic synthetic difficulties. Here, a modified Hiyama coupling reaction was developed to synthesize GDY aerogel via in-situ deprotection of trimethylsilane groups and subsequent freeze-drying. The synthesized GDY aerogel has a low density of ∼12 mg cm^-3, a high specific surface area of ∼909 m² g^-1, and a porosity of ∼98%, which is superior to other GDY nanomaterials. The adsorption capacity of GDY aerogel toward H₂, CO₂, and CH₄ is investigated, and competitive adsorption abilities are obtained.

Step by Step Induced Growth of Zinc-Metal Interface on Graphdiyne for Aqueous Zinc-Ion Batteries

Rechargeable aqueous zinc ion batteries (AZIBs) promise high energy density, low redox potential, low cost and safety; however, their cycle performances are seriously insufficient to restrict the progress in this field. We propose a new concept of atomic electrode formed on the graphdiyne (GDY). This new idea electrode was synthesized by selectively, uniformly, and stably anchoring Zn atoms on GDY at the beginning of plating. The Zn atoms are induced to grow into larger size Zn clusters, which continue to grow into nanoflat. Finally, a new heterojunction interface is formed on GDY without any Zn dendrites and side reactions, even at high current densities. Such stepwise induction of growth greatly suppresses the formation of Zn dendrites, resulting in high electroplating/stripping reversibility and lifespan of AZIBs.

Gradient Graphdiyne Induced Copper and Oxygen Vacancies in Cu0.95 V2 O5 Anodes for Fast-Charging Lithium-Ion Batteries

Vacancies can significantly affect the performance of metal oxide materials. Here, a gradient graphdiyne (GDY) induced Cu/O-dual-vacancies abundant Cu_0.95 V₂ O₅ @GDY heterostructure material has been prepared as a competitive fast-charging anode material. Cu_0.95 V₂ O₅ self-catalyzes the growth of gradient GDY with rich alkyne-alkene complex in the inner layer and rich alkyne bonds in the outer layer, leading to the formation of Cu and O vacancies in Cu_0.95 V₂ O₅ . The synergistic effect of vacancies and gradient GDY results in the electron redistribution at the hetero-interface to drive the generation of a built-in electric field. Thus, the Li-ion transport kinetics, electrochemical reaction reversibility and Li storage sites of Cu_0.95 V₂ O₅ are greatly enhanced. The Cu_0.95 V₂ O₅ @GDY anodes show excellent fast-charging performance with high capacities and negligible capacity decay for 10 000 cycles and 20 000 cycles at extremely high current densities of 5 A g^-1 and 10 A g^-1 , respectively. Over 30 % of capacity can be delivered in 35 seconds.

Graphdiyne-Based Single-Atom Catalysts with Different Coordination Environments

As a special carbon material, graphdiyne (GDY) features the superiorities of incomplete charge transfer effect on the atomic level, tunable electronic structure and anchoring metal atoms directly with organometallic coordination bonds M (metal)-C (alkynyl carbon in GDY), providing it an ideal platform to construct single-atom catalysts (ACs). The coordination environment of single atoms anchored on GDY plays a key role in their catalytic performance. The mini-review highlights state-of-the-art progress in the rational design of GDY-based ACs and their applications, and mainly reveals the relationship between the coordination engineering of the GDY-based ACs and corresponding catalytic performance. Finally, some prospects concerning the future development of GDY-based ACs in energy conversion are also discussed.

Electronic Oxide-Support Strong Interactions in the Graphdiyne-Supported Cuprous Oxide Nanocluster Catalyst

The interfacial interaction in supported catalysts is of great significance for heterogeneous catalysis because it can induce charge transfer, regulate electronic structure of active sites, influence reactant adsorption behavior, and eventually affect the catalytic performance. It has been theoretically and experimentally elucidated well in metal/oxide catalysts and oxide/metal inverse catalysts, but is rarely reported in carbon-supported catalysts due to the inertness of traditional carbon materials. Using an example of a graphdiyne-supported cuprous oxide nanocluster catalyst (Cu₂O NCs/GDY), we herein demonstrate the strong electronic interaction between them and put forward a new type of electronic oxide-graphdiyne strong interaction, analogous to the concept of electronic oxide/metal strong interactions in oxide/metal inverse catalysts. Such electronic oxide-graphdiyne strong interaction can not only stabilize Cu₂O NCs in a low-oxidation state without aggregation and oxidation under ambient conditions but also change their electronic structure, resulting in the optimized adsorption energy for reactants/intermediates and thus leading to improved catalytic activity in the Cu(I)-catalyzed azide-alkyne cycloaddition reaction. Our study will contribute to the comprehensive understanding of interfacial interactions in supported catalysts.

A Deprotection-free Method for High-yield Synthesis of Graphdiyne Powder with In Situ Formed CuO Nanoparticles

With a direct band gap, superior charge carrier mobility, and uniformly distributed pores, graphdiyne (GDY) has stimulated tremendous interest from the scientific community. However, its broad application is greatly limited by the complicated multistep synthesis process including complex deprotection of hexakis-[(trimethylsilyl)ethynyl]benzene (HEB-TMS) and peeling of GDY from the substrates. Here, we describe a deprotection-free strategy to prepare GDY powder by directly using HEB-TMS as the monomer. When CuCl was used as the catalysts in DMF solvent, the yield of GDY powder reached ≈100 %. More interestingly, uniformly dispersed CuO nanoparticles with an average diameter of ≈2.9 nm were in situ formed on GDY after the reaction. The prepared CuO/GDY was demonstrated an excellent co-catalyst for photocatalytic hydrogen evolution, comparable to the state-of-art Pt co-catalyst. The deprotection-free approach will widen the use of GDY and facilitate its scaling up to industrial level.

Controlled growth of a high selectivity interface for seawater electrolysis

Overall seawater electrolysis is an important direction for the development of hydrogen energy conversion. The key issues include how to achieve high selectivity, activity, and stability in seawater electrolysis reactions. In this report, the heterostructures of graphdiyne-RhO_x-graphdiyne (GDY/RhO_x/GDY) were constructed by in situ-controlled growth of GDY on RhO_x nanocrystals. A double layer interface of sp-hybridized carbon-oxide-Rhodium (sp-C∼O-Rh) was formed in this system. The microstructures at the interface are composed of active sites of sp-C∼O-Rh. The obvious electron-withdrawing surface enhances the catalytic activity with orders of magnitude, while the GDY outer of the metal oxides guarantees the stability. The electron-donating and withdrawing sp-C∼O-Rh structures enhance the catalytic activity, achieving high-performance overall seawater electrolysis with very small cell voltages of 1.42 and 1.52 V at large current densities of 10 and 500 mA cm^-2 at room temperatures and ambient pressures, respectively. The compositional and structural superiority of the GDY-derived sp-C-metal-oxide active center offers great opportunities to engineer tunable redox properties and catalytic performance for seawater electrolysis and beyond. This is a typical successful example of the rational design of catalytic systems.

Rhodium nanocrystals on porous graphdiyne for electrocatalytic hydrogen evolution from saline water

The realization of the efficient hydrogen conversion with large current densities at low overpotentials represents the development trend of this field. Here we report the atomic active sites tailoring through a facile synthetic method to yield well-defined Rhodium nanocrystals in aqueous solution using formic acid as the reducing agent and graphdiyne as the stabilizing support. High-resolution high-angle annular dark-field scanning-transmission electron microscopy images show the high-density atomic steps on the faces of hexahedral Rh nanocrystals. Experimental results reveal the formation of stable sp-C~Rh bonds can stabilize Rh nanocrystals and further improve charge transfer ability in the system. Experimental and density functional theory calculation results solidly demonstrate the exposed high active stepped surfaces and various metal atomic sites affect the electronic structure of the catalyst to reduce the overpotential resulting in the large-current hydrogen production from saline water. This exciting result demonstrates unmatched electrocatalytic performance and highly stable saline water electrolysis.

Ultrafast Sulfur Mustard Simulant Gas Fluorescent Chemosensors Based on Triazole AIEE Material with High Selectivity and Sensitivity at Room Temperature

Herein, a novel blue aggregation-induced enhanced emission (AIEE) material 4-N-(naphthalen-l-yl)-3,5-bis(4-N-phenyl-1-naphthylamine)phenyl-4H-1,2,4-triazole (NDTAZ) is developed and used as a fluorescent chemosensor for sulfur mustard (SM) simulant 2-chloroethyl ethyl sulfide (2-CEES) vapor. The NDTAZ chemosensor is designed by introducing an electron-donating N-phenyl-1-naphthylamine group at 3 and 5 position of 4H-1,2,4-triazole (TAZ) to enhance the nucleophilicity of the TAZ group, and a naphthalene ring is connected to 4 position of the TAZ group to construct an AIEE molecule. The NDTAZ films show extraordinary stability and then are further used as reliable and portable fluorescent chemosensors. Upon exposure to 2-CEES vapor, the NDTAZ chemosensor exhibits an instantaneous fluorescence response (not more than 1 s). What should be noted is that this fluorescent chemosensor realizes the visualized detection of fluorescent color change from blue to green at "room temperature", which is rarely reported. The limit of detection is estimated to be 0.55 ppm, which is below the AEGL-1 (0.6 ppm for 1 min) safety ceiling level to SM exposure. Moreover, the NDTAZ chemosensor shows high selectivity toward 2-CEES vapor over closely related substances, including alkylating agents, aryl halide compounds, sulphur-containing compounds, and nerve agent mimics. More impressively, the NDTAZ chemosensor demonstrates good recyclability by water treatment. Also, the sensing mechanism is adequately proved by using multiple experimental methods and theoretical calculation. In addition, the NDTAZ-based facile filter paper-constructed test strips are fabricated for real-time and on-spot detection of leaked 2-CEES gas specifically. Therefore, this fluorescent chemosensor with excellent sensing performance greatly advances the practical detection of SM species at room temperature.

Platinum-Ruthenium Single Atom Alloy as a Bifunctional Electrocatalyst toward Methanol and Hydrogen Oxidation Reactions

The precise regulation for the structural properties of nanomaterials at the atomic scale is an effective strategy to develop high-performance catalysts. Herein, a facile dual-regulation approach was developed to successfully synthesize Ru₁Pt_n single atom alloy (SAA) with atomic Ru dispersed in Pt nanocrystals. High-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine structure demonstrated that Ru atoms were dispersed in Pt nanocrystals as single atoms. Impressively, the Ru₁Pt_n-SAA exhibited an ultrahigh specific activity (23.59 mA cm^-2) and mass activity (2.805 mA/μg_-PtRu) for methanol oxidation reaction (MOR) and exhibited excellent exchange current density activity (1.992 mA cm^-2) and mass activity (4.71 mA/μg_-PtRu) for hydrogen oxidation reaction (HOR). Density functional theory calculations revealed that the introduction of Ru atoms greatly reduced the reaction free energy for the decomposition of water molecules, which promoted the removal of CO* in the MOR process and adjusted the Gibbs free energy of hydrogen and hydroxyl adsorption to promote the HOR. Our work provided an effective idea for the development of high performance electrocatalysts.

NiCoPd Inlaid NiCo-Bimetallene for Efficient Electrocatalytic Methanol Oxidation

Pd-based metallenes have attracted great attention recently as newly burgeoning two-dimensional (2D) materials, attributed to their significantly increased active surface areas and intrinsic electrocatalytic activities. Therefore, they could be used as a potential candidate as the high-performance electrocatalyst for methanol oxidation reactions (MORs) in the direct methanol fuel cell. Herein, a new strategy is proposed to fabricate NiCoPd inlaid NiCo-bimetallene (NiCoPd/NiCo-bimetallene) by the structure directing effect of 18-crown-6 ether under an ultrasonic-pulse interface together with the HCHO reduction and atom-diffusion-aging process. NiCoPd ternary-alloys with uniformly dispersed Pd active sites are decorated onto NiCo-bimetallenes, achieving remarkably enhancing the effective utilization of Pd atoms. What is more, the intrinsic activity is enhanced by the "bifunctional mechanism" of NiCo-bimetallene adsorption of intermediate species and increased Pd-active sites. Moreover, the anti-CO poisoning ability is optimized through the "alloying ligand effect" of NiCoPd. Therefore, the NiCoPd/NiCo-bimetallene exhibits excellent mass activity for MOR, which is higher than commercial Pd/C. This work suggests a new way of the Pd-based metallenes catalyst approach to the efficient electrocatalytic MOR.

Graphdiyne Electrochemistry: Progress and Perspectives

Graphdiyne, a carbon allotrope, was synthesized in 2010 for the first time. It consists of two acetylene bonds between adjacent benzene rings. Graphdiyne and its composites thus exhibit ultrahigh intrinsic electrochemical activities. As "star" electrode materials, they have been utilized for various electrochemical applications. With the aim of giving a full screen of graphdiyne electrochemistry, this review starts from the history of graphdiyne materials, followed by their structural and electrochemical features. Recent progress and achievements in the synthesis of graphdiyne materials and their composites are overviewed. Subsequently, various electrochemical applications of graphdiyne materials and their composites are summarized, covering those in the fields of electrochemical energy conversion, electrochemical energy storage, and electrochemical sensing. The perspectives of graphdiyne electrochemistry are also discussed and outlined.