Optimizing Pt-Based Alloy Electrocatalysts for Improved Hydrogen Evolution Performance in Alkaline Electrolytes: A Comprehensive Review

PtO nanoclusters on ultra-thin 2D Mo2C enhance hydrated cation interaction for superior alkaline hydrogen evolution reaction

Platinum oxide (PtO) is regarded as an effective catalyst beyond platinum metal for the hydrogen evolution reaction (HER). However, slow kinetics and structural instability limit its wide application as alkaline electrocatalyst. Herein, PtO nanoclusters decorated ultrathin two-dimensional (2D) Mo2C with a Pt concentration of 0.98 wt% (Mo2C-PtO) is designed and prepared to overcome these hurdles. The Mo2C-PtO catalyst shows significant interfacial charge reconstruction and strong electrostatic interaction with hydrated ions and exhibits remarkable HER performance with an ultra-low overpotential of 5, 64 and 329 mV at 10, 100 and 1000 mA cm-2 and a small Tafel slope of 25 mV dec-1 in alkaline solution, as well as the long-term durability of hydrogen production at 500 mA cm-2. In situ Raman scattering and theoretical calculation reveal the fast migration and dissociation of cationic hydration water at interface, which accelerates Volmer reaction. The key intermediates of OH* and H* transfer rapidly from the interface to Mo2C and PtO, respectively, which increases the availability of interfacial sites and facilitates the fast Volmer-Tafel mechanism. This study highlights the potential of carbide-supported PtO nanoclusters as highly efficient catalysts for alkaline hydrogen production and offers insights into the interfacial water evolution mechanism.

Reductive Supramolecular In Situ Construction of Nano-Platinum Effectively Couples Cathodic Hydrogen Evolution and Anodic Alcohol Oxidation

The deployment of high-performance catalysts and the acceleration of anodic reaction kinetics are key measures to achieve maximum energy efficiency in overall water electrolysis hydrogen production systems. Here, an innovative strategy is developed by directly constructing a supramolecular framework embedded with boron clusters and cucurbituril as reducing agent. This approach enabled the in situ conversion of Pt⁴⁺ into highly dispersed, small-sized nano-platinum, which are subsequently distributed on a boron-carbon-nitrogen (BCN) matrix. The resulting Pt/BNHCSs catalyst demonstrates the ability to facilitate electrocatalytic water splitting for hydrogen production across multiple scenarios while simultaneously accelerating the anodic methanol oxidation kinetics, significantly outperforming commercial Pt/C catalyst in various aspects. The cathodic hydrogen evolution-anodic methanol oxidation coupling system constructed using the Pt/BNHCSs greatly reduces the overall energy consumption of the electrolysis system. In situ attenuated total reflection Fourier transform infrared and online differential electrochemical mass spectrometry reveals that the catalyst interface enhances H₂O adsorption and promotes the CH₃OH→CO conversion process, and density functional theory calculations indicated that the BCN support facilitated the evolution of H₂O to H₂ and CH₃OH to CO, elucidating the mechanism by which Pt/BNHCSs simultaneously promoted hydrogen production and methanol oxidation.

Pt(OH)x Coordination Engineering of Bifunctional Pt/NiFe LDH-O Catalyst for Robust Water Splitting

Modulating the coordination environment of metal active sites and adjacent atoms significantly enhances the catalytic activity of heterogeneous catalysts owing to the local synergistic effect between metal sites and supports. While layered double hydroxide (LDH)-supported Pt catalysts exhibit complementary advantages and exceptional performance in overall water splitting (OWS), the absence of a robust coordination structure between Pt and LDH constrains their activity and stability. Herein, we report a coordination engineering strategy to alter the coordination structure of Pt on the surface of NiFe LDH using atomic layer deposition (ALD) for OWS. The synthesized Pt/NiFe LDH-O catalyst, featuring the 2-coordinate Pt-OH and 6-coordinate Pt-Pt, exhibits a η10 = 14 mV for hydrogen evolution reaction (HER), a η100 = 287 mV for oxygen evolution reaction (OER), and an effective OWS activity (η10 = 1.496 V) for over 200 h. Combining structural and electrochemical characterizations, we confirmed that the coordination engineering affected the nucleation and growth of Pt on NiFe LDH, leading to a decrease of Pt-OH coordination and an increase of Pt-Pt coordination, thereby enhancing the hydrolysis capability of Pt and shifting the rate-determining step (RDS) from the Volmer step to the Heyrovsky step, which contributed to the excellent OWS performance. The density functional theory (DFT) results demonstrated that the electronic structure of NiFe LDH is considerably regulated by an increase in Pt-Pt coordination, facilitating charge redistribution. Our investigation provides deep insights into the coordination regulating the electrocatalytic activity of LDH-supported metal catalysts.

Ni4Mo nanoparticles embedded in N-doped carbon nanotubes growing on Ni4Mo/MoO2 micropillars for durable hydrogen evolution

N-doped carbon nanotubes embedding Ni4Mo particles at the tips growing on Ni4Mo/MoO2 micropillars were achieved as a highly efficient HER electrocatalyst. This well-designed NCNTs@Ni4Mo/MoO2 heterostructure catalyst exhibits excellent durability and high activity toward the hydrogen evolution reaction.

Proper aggregation of Pt is beneficial for the epoxidation of styrene by O2 over Ptx/γ-Al2O3 catalysts

The dispersion of metal catalysts has multiple effects on catalytic performance, and higher dispersions do not necessarily imply better performance. Herein, we report the epoxidation reaction of styrene over supported platinum catalysts as an example. Compared with the Pt1/γ-Al2O3 catalyst, the Ptn/γ-Al2O3 catalyst with a larger Pt cluster size showed a much better performance. Combining the results of various characterizations and density functional theory calculations, Ptn/γ-Al2O3 was found to be more favorable for oxygen adsorption and activation to generate singlet oxygen species, further promoting the styrene oxidation reaction to styrene oxide in terms of kinetics. In contrast the metallic center of Pt1 in Pt1/γ-Al2O3 was too small to efficiently activate the diatomic oxygen molecule. These insights provide valuable guidance for designing high-performance metal catalysts.

In Situ SERS Monitoring and Heterogeneous Catalysis Verification of Pd-Catalyzed Suzuki-Miyaura Reaction via Bifunctional "Black Raspberry-like" Plasmonic Nanoreactors

Constructing materials that possess both catalytic properties and surface plasmonic active structures presents an essential requirement in the field of in situ surface-enhanced Raman spectroscopy (SERS) monitoring. In this work, we developed a novel black raspberry-like bifunctional nanoreactor platform (HPRS@Au-Pd) with enhanced surface-enhanced Raman spectroscopy (SERS) activity (EF = 3.11 × 109) and excellent catalytic performance (e.g., |K| = 1.72 × 10-2 s-1 for 4-BTP). This platform enables sensitive and real-time monitoring of Suzuki reactions, providing an efficient and stable system for mechanistic investigations. By fitting a first-order kinetic model, we quantitatively analyzed the reaction kinetics of haloarenes on Pd NPs, revealing the direct involvement of surface-bound Pd NPs in the catalytic process. Furthermore, 4MPBA-blocking experiments using haloarenes devoid of functional groups demonstrated the absence of catalytic activity from dissolved Pd species, conclusively supporting the heterogeneous nature of the reaction. This work extends the applicability of the conclusion regarding heterogeneous catalysis to a broader range of substrates, offering valuable insights into the design and optimization of dual-functional nanoreactors. Beyond the Suzuki reactions, the versatility of this platform opens avenues for applications in other catalytic reactions, showcasing its potential in advanced catalytic studies and real-time monitoring.

Electrocatalytic biomass upgrading coupled with hydrogen evolution and CO2 reduction

Clean energy production and CO2 utilization have attracted increasing interest. Electrocatalysis represents an effective way to produce green hydrogen from water and reduce CO2 to valuable compounds. However, for either the hydrogen evolution reaction (HER) or the CO2 reduction reaction (CO2RR), the reaction efficiency is significantly limited by the slow kinetics of the oxygen evolution reaction (OER) at the anode, which consumes most of the input energy. Therefore, great efforts have been made to replace the OER with organic oxidation reactions at the anode to decrease the reaction energy barrier. Biomass has an advantage of broad source, and when it is employed as an OER alternative in the anode oxidation reactions, not only can the reduction reaction efficiency at the cathode including the HER and CO2RR be enhanced but high-value chemicals can also be obtained, representing an attractive OER alternative. This review comprehensively summarizes the recent achievements in electrocatalytic biomass upgrading coupled with the HER and CO2RR, cataloged based on the type of biomass. The design of electrocatalysts for such coupled reaction systems is discussed. Finally, the challenges and perspectives in the field of this energy-saving and value-added coupling system are provided to inspire more efforts in pushing forward the development of this field.

Finely Tailoring Metal-Support Interactions via Transient High-Temperature Pulses

Metal-support interactions (MSI) play a crucial role in enhancing the catalytic activity and stability of metal catalysts by establishing a stable metal-oxide interface. However, precisely controlling MSI at the atomic scale remains a significant challenge, as how to construct an optimal MSI is still not fully understood: Both insufficient and excessive MSI showed inferior catalytic performance. In this study, we propose finely tuning MSI using temporal-precise transient high-temperature pulse heating. Using Pt/CeO2 as a model system, we systematically investigate how variations in pulse duration and atmosphere influence the reconstruction of the metal-support interface and MSIs. This leads to the formation of two distinct types of MSI: (1) strong MSI (SMSI, Pt@CeO2) and (2) reactive MSI (RMSI, Pt5Ce@CeO2), each with unique compositions, structures, and electrochemical behaviors. Notably, Pt5Ce@CeO2 with RMSI exhibits remarkable catalytic performance in the alkaline hydrogen evolution, showing an overpotential of -29 mV and stable operation for over 300 h at -10 mA·cm-2. Theoretical studies reveal that alloying Pt with Ce to form Pt5Ce modifies the electronic structure of Pt, shifting the d-band center to optimize the adsorption and dissociation of intermediates, thereby reducing the reaction energy barrier. Moreover, the intimate interaction of Pt5Ce with CeO2 further improves the activity and stability. Our strategy enables precise, stepwise, and controllable regulation of MSIs, providing insights for the development of highly efficient and durable heterostructured catalysts with optimal MSI for a wide range of catalytic applications.

Laser Ultrafast Confined Alloying of Sub-5 nm RuM (M = Cu, Rh, and Pd) Particles on Carbon Nanotubes for Hydrogen Evolution Reaction

Thermodynamic immiscibility is a challenge for intermetallic alloying of sub-5 nm Ru-based alloys, which are excellent electrochemical catalysts for water splitting. In this study, nanosecond laser ultrafast confined alloying (LUCA) is proposed to break the immiscible-to-miscible transition limit in the synthesis of carbon nanotubes (CNTs) supported sub-5 nm bimetallic RuM (M = Cu, Rh, and Pd) alloy nanoparticles (NPs). The alloying of non-noble metal Cu with varying atomic ratios of RuCu alloys is appealing owing to the low price of Cu and cost-effective synthesis for large-scale practical applications. Benefiting from the synergistic alloying effect and resultant H/OH binding energy alteration, the Ru95Cu5/CNTs catalysts display excellent electrocatalytic alkaline hydrogen evolution reaction (HER) activity with an overpotential of 17 mV and Tafel slope of 28.4 mV dec-1 at 10 mA cm-2, and high robustness over long-term 5000 cyclic voltammetry cycles. The performance is much better than LUCA-synthesized CNTs-supported Ru86Rh14, Ru89Pd11, Ru, and Cu NPs catalysts, commercial benchmark 20% Pt/C, and other mainstream Ru-based catalysts including wet chemistry-synthesized RuRh particles (overpotential of 25 mV, Tafel slope of 47.5 mVdec-1) and RuCu/CNTs (overpotential of 39 mV) synthesized using the flash Joule heating method, indicating the great potential of LUCA for screening new classes of HER catalysts.

Atomic Gap-State Engineering of MoS2 for Alkaline Water and Seawater Splitting

Transition-metal dichalcogenides (TMDs), such as molybdenum disulfide (MoS2), have emerged as a generation of nonprecious catalysts for the hydrogen evolution reaction (HER), largely due to their theoretical hydrogen adsorption energy close to that of platinum. However, efforts to activate the basal planes of TMDs have primarily centered around strategies such as introducing numerous atomic vacancies, creating vacancy-heteroatom complexes, or applying significant strain, especially for acidic media. These approaches, while potentially effective, present substantial challenges in practical large-scale deployment. Here, we report a gap-state engineering strategy for the controlled activation of S atom in MoS2 basal planes through metal single-atom doping, effectively tackling both efficiency and stability challenges in alkaline water and seawater splitting. A versatile synthetic methodology allows for the fabrication of a series of single-metal atom-doped MoS2 materials (M1/MoS2), featuring widely tunable densities with each dopant replacing a Mo site. Among these (Mn1, Fe1, Co1, and Ni1), Co1/MoS2 demonstrates outstanding HER performance in both alkaline and seawater alkaline media, with overpotentials at a mere 159 and 164 mV at 100 mA cm-2, and Tafel slopes at 41 and 45 mV dec-1, respectively, which surpasses all reported TMD-based nonprecious materials and benchmark Pt/C catalysts in HER efficiency and stability during seawater splitting, which can be attributed to an optimal gap-state modulation associated with sulfur atoms. Experimental data correlating doping density and dopant identity with HER performance, in conjunction with theoretical calculations, also reveal a descriptor linked to near-Fermi gap state modulation, corroborated by the observed increase in unoccupied S 3p states.

Ohmic Contact Heterostructures Immobilized Pt Single Atoms for Boosting Alkaline Hydrogen Evolution Reaction

Pt single-atoms catalysts have been widely confirmed as ideal electrocatalysts for high-efficiency hydrogen evolution reaction (HER), but their activity and durability at high current density remain great challenges, especially in alkaline media. Herein, a unique Ohmic contact heterostructure is fabricated by integrating Ni and NiO to immobilize Pt single-atoms (Ni-NiO-Pt) via Pt-O4 coordination for boosting the alkaline HER. Owing to transient high temperature and pressure in the laser ablation process, Ohmic contact heterojunctions are constructed at the interfaces between metal Ni core and nanoporous semiconducting NiO shell with adequate oxygen vacancies. The large work function difference triggers the electron transfer from Ni to Pt-decorated NiO, which dramatically eliminates the electron conduction impedance and regulates the charge redistribution. Density functional theory calculation unveils that the multiple regulations of energy barrier and charge redistribution on Ohmic contact endow Ni-NiO-Pt with outstanding electrical conductivity and favorable hydrogen binding energy. Consequently, Ni-NiO-Pt displays superior alkaline HER performances with an overpotential of 23.54 mV at 10 mA cm-2 and protruding durability for 75 h at 500 mA cm-2, drastically outperforming commercial Pt/C and most reported HER electrocatalysts. The immobilization of Pt single-atoms on Ohmic contact opens up an avenue toward the rational design of high-efficiency electrocatalysts.

Mono-/Bimetallic Doped and Heterostructure Engineering for Electrochemical Energy Applications

Designing efficient materials is crucial to meeting specific requirements in various electrochemical energy applications. Mono-/bimetallic doped and heterostructure engineering have attracted considerable research interest due to their unique functionalities and potential for electrochemical energy conversion and storage. However, addressing material imperfections such as low conductivity and poor active sites requires a strategic approach to design. This review explores the latest advancements in materials modified by mono-/bimetallic doped and heterojunction strategies for electrochemical energy applications. It can be subdivided into three key points: (i) the regulatory mechanisms of metal doping and heterostructure engineering for materials; (ii) the preparation methods of materials with various engineering strategies; and (iii) the synergistic effects of two engineering approaches, further highlighting their applications in supercapacitors, alkaline ion batteries, and electrocatalysis. Finally, the review concludes with perspectives and recommendations for further research to advance these technologies.

Ultrafast H-Spillover in Intermetallic PtZn Induced by the Local Disorder for Excellent Electrocatalytic Hydrogen Evolution Performance

Ordered intermetallic Platinum-Zinc (PtZn) shows potential in hydrogen evolution reaction (HER), but faces a huge challenge in activity enhancement due to the H-repulsion properties of Zinc (Zn). Here, local disorder in ordered intermetallic PtZn nanoparticles confined in N-doped porous carbon (I-PtZn@NPC) via a confinement-high-temperature pyrolysis strategy is realized to boost the HER performance. Experiments and calculations demonstrate that the local substitution of Pt atoms for Zn atoms creates an ultra-short H-spillover channel (Pt site→Pt-Zn bridge site →Zn site). Benefiting from such an ultra-fast H-migration from Pt site to Zn site, I-PtZn@NPC exhibits enhanced intrinsic activity with an ultralow overpotential (η10: 2.3 mV, η100: 24 mV) than commercial Pt black catalyst. Furthermore, a 25 cm2 commercial proton exchange membrane (PEM) electrolyzer equipped with I-PtZn@NPC achieved stable operation at 1.60 Vcell for 200 h at a current density of 1 A cm⁻2. This design of local Zn disorder in the ordered intermetallic PtZn sheds new light on the rational development of efficient Zn-based alloy HER electrocatalysts.

Impact of confining hydrogen molecule inside fullerenes: A glance through DFT study

CONTEXT

In this work, we have studied different properties of a series of fullerenes, from C24 to C50 by confining hydrogen molecule inside their cavity. The compression of the hydrogen molecule upon encapsulation is evidenced by its altered bond length, while a slight expansion of the fullerene cages due to H2 confinement is also noted. The chemical reactivity parameters of both the empty and H2 confined fullerenes are computed, alongside an examination of the energy components through energy decomposition analysis. Analysis of the absorption spectra indicated that both H2 encapsulated and empty fullerenes exhibited absorption in the UV region. Nevertheless, the inclusion of H2 within the fullerene cages appeared to have minimal influence on the reactivity parameters and absorption spectra, as evidenced by the comparison between the sets of empty and H2-confined fullerenes.

METHODS

The computational work including the geometry optimization, followed by the frequency analysis and other parameters has been achieved using Gaussian09 software. For doing these calculations, B3LYP and CAM-B3LYP functionals along with 6-311 + G(d,p) basis set is used. In addition, MULTIWFN software has been considered for studying bonding analysis and energy decomposition analysis for the systems.

Dynamic Self-Reconstruction Heterostructures: Boosting the High-Stability for Hydrogen Evolution of NiMo Alloys in Acidic Environments

Electrocatalytic water splitting is considered one of the most promising approaches for large-scale hydrogen production. However, designing transition metal catalysts with high durability under acidic conditions remains a significant challenge. The durability of the catalyst is closely related to the changes of the catalyst during its operation, and constructing effective surface reconstruction strategies can help address the durability issues of transition metals in acidic hydrogen evolution reactions (HER). Herein, the spontaneous formation of surface-reconstructed heterostructures of NiMo alloys is reported during the HER in acidic media. The surface of the catalyst is characterized by the presence of Ni/Mo metal nanoparticles and NixMoyOz nanosheets, which coexist as HER proceeds. Notably, the E-Ni90Mo10/CC After 96 h catalyst demonstrates a significantly reduced overpotential of 56.84 mV at 10 mA cm⁻2 in 0.5 m sulfuric acid, which is better than other E-Ni90Mo10/CC counterparts. Both experimental data and theoretical calculations suggest that these spontaneously formed heterostructures are helpful for optimizing hydrogen adsorption. Furthermore, the downward shift of the d-band center within the heterostructure (Ni90Mo10/NixMoyOz) is found to facilitate the desorption of intermediate products, thereby enhancing the overall HER activity. This work provides a new perspective for designing highly durable transition metal catalysts for acidic HER.

In Situ Hydroxide Growth over Nickel-Iron Phosphide with Enhanced Overall Water Splitting Performances

In this work, three dimensional (3D) self-supported Ni-FeOH@Ni-FeP needle arrays with core-shell heterojunction structure are fabricated via in situ hydroxide growth over Ni-FeP surface. The as-prepared electrodes show an outstanding oxygen evolution reaction (OER) performance, only requiring the low overpotential of 232 mV to reach 200 mA cm-2 with the Tafel slop of 40 mV dec-1. For overall water splitting, an alkaline electrolyzer with these electrodes only requires a cell voltage of 2.14 V to reach 1 A cm-2. Mechanistic investigations for such excellent electrocatalytic performances are utilized by in situ Raman spectroscopy in conjunction with density functional theory (DFT) calculations. The computation results present that Ni-FeOH@Ni-FeP attains better intrinsic conductivity and the D-band center (close to that of the ideal catalyst), thus giving superior excellent catalytic performances. Likewise, the surface Ni-FeOH layer can improve the structural stability of Ni-FeP cores and attenuate the eventual formation of irreversible FeOOH products. More importantly, the appearance of FeOOH intermediates can effectively decrease the energy barrier of NiOOH intermediates, and then rapidly accelerate the sluggish reaction dynamics, as well as further enhance the electrocatalytic activities, reversibility and cycling stability.

Insights into the pH effect on hydrogen electrocatalysis

Hydrogen electrocatalytic reactions, including the hydrogen evolution reaction (HER) and the hydrogen oxidation reaction (HOR), play a crucial role in a wide range of energy conversion and storage technologies. However, the HER and HOR display anomalous non-Nernstian pH dependent kinetics, showing two to three orders of magnitude sluggish kinetics in alkaline media compared to that in acidic media. Fundamental understanding of the origins of the intrinsic pH effect has attracted substantial interest from the electrocatalysis community. More critically, a fundamental molecular level understanding of this effect is still debatable, but is essential for developing active, stable, and affordable fuel cells and water electrolysis technologies. Against this backdrop, in this review, we provide a comprehensive overview of the intrinsic pH effect on hydrogen electrocatalysis, covering the experimental observations, underlying principles, and strategies for catalyst design. We discuss the strengths and shortcomings of various activity descriptors, including hydrogen binding energy (HBE) theory, bifunctional theory, potential of zero free charge (pzfc) theory, 2B theory and other theories, across different electrolytes and catalyst surfaces, and outline their interrelations where possible. Additionally, we highlight the design principles and research progress in improving the alkaline HER/HOR kinetics by catalyst design and electrolyte optimization employing the aforementioned theories. Finally, the remaining controversies about the pH effects on HER/HOR kinetics as well as the challenges and possible research directions in this field are also put forward. This review aims to provide researchers with a comprehensive understanding of the intrinsic pH effect and inspire the development of more cost-effective and durable alkaline water electrolyzers (AWEs) and anion exchange membrane fuel cells (AMFCs) for a sustainable energy future.

Ultra-Small High-Entropy Alloy as Multi-Functional Catalyst for Ammonia Based Fuel Cells

Ammonia fuel cells using carbon-neutral ammonia as fuel are regarded as a fast, furious, and flexible next-generation carbon-free energy conversion technology, but it is limited by the kinetically sluggish ammonia oxidation reaction (AOR), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER). Platinum can efficiently drive these three types of reactions, but its scale-up application is limited by its susceptibility to poisoning and high cost. In order to reduce the cost and alleviate poisoning, incorporating Pt with various metals proves to be an efficient and feasible strategy. Herein, PtFeCoNiIr/C trifunctional high-entropy alloy (HEA) catalysts are prepared with uniform mixing and ultra-small size of 2 ± 0.5 nm by Joule heating method. PtFeCoNiIr/C exhibits efficient performance in AOR (Jpeak = 139.8 A g-1 PGM), ORR (E1/2 = 0.87 V), and HER (E10 = 20.3 mV), outperforming the benchmark Pt/C, and no loss in HER performance at 100 mA cm-2 for 200 h. The almost unchanged E1/2 in the anti-poisoning test indicates its promising application in real fuel cells powered by ammonia. This work opens up a new path for the development of multi-functional electrocatalysts and also makes a big leap toward the exploration of cost-effective device configurations for novel fuel cells.

Dimensionality-Tailored Ferromagnetism in Quasi-Two-Dimensional MnSe2 for the Magnetoelectrochemical Hydrogen Evolution Reaction in Alkaline Media

The application of an external magnetic field to the cathode shows great promise in facilitating the hydrogen evolution reaction (HER) via water electrolysis. However, the criteria for designing such cathodes are still under investigation. Among various aspects, understanding the effect of different magnetic states of the cathode material is crucial, especially for the HER in alkaline conditions, which possesses different reaction steps compared to that in acidic conditions. Herein, we present MnSe2 as a cathode material for the magneto-electrocatalytic HER in alkaline media, utilizing its dimension-dependent magnetic phase transition. By tailoring its dimensionality, we have achieved room-temperature ferromagnetism in its quasi-two-dimensional (2D) form, whereas its bulk counterpart exhibits paramagnetism. Upon being subjected to a low external magnetic field of 0.4 T at -182 mV (vs RHE) overpotential, quasi-2D MnSe2 exhibited a 120% improvement in current density compared to itself at zero magnetic field, while negligible changes were observed in the bulk material. This performance enhancement under a magnetic field could originate from the higher spin polarization of the ferromagnetic catalyst. This work signifies a conceptual advancement of the catalyst's spin state in magnetically enhanced electrocatalytic reaction kinetics.

Defective Carbon Nitride with Dual-surface Engineering for Highly Efficient Photocatalytic Hydrogen Evolution under Visible Light Irradiation

Defective carbon nitride (DCN-x) was synthesized through a dual-surface engineering process consisting of nitric acid treatment followed by high-temperature calcination. This process endowed DCN-x with a porous structure and a larger surface area than that of pure graphite carbon nitride (CN), enhancing its visible light absorption and reducing the electron-hole recombination rate. Consequently, DCN-x demonstrated a significantly more efficient photocatalytic hydrogen evolution, with the optimum sample, DCN-600, achieving an activity 55.9 times greater than that of pure CN, while maintaining excellent photocatalytic stability. Furthermore, the presence of tri-s-triazine (heptazine) structures within the CN's in-plane structure was identified as a critical factor for band gap optimization, suggesting new avenues for the synthesis of carbon nitride variants with enhanced photocatalytic performance.

2D PtRhPb Mesoporous Nanosheets with Surface-Clean Active Sites for Complete Ethanol Oxidation Electrocatalysis

The development of active and selective metal electrocatalysts for complete ethanol oxidation reaction (EOR) into desired C1 products is extremely promising for practical application of direct ethanol fuel cells. Despite some encouraging achievements, their activity and selectivity remain unsatisfactory. In this work, it is reported that 2D PtRhPb mesoporous nanosheets (MNSs) with anisotropic structure and surface-clean metal site perform perfectly for complete EOR electrocatalysis in both three-electrode and two-electrode systems. Different to the traditional routes, a selective etching strategy is developed to produce surface-clean mesopores while retaining parent anisotropy quasi-single-crystalline structure without the mesopore-forming surfactants. This method also allows the general synthesis of surface-clean mesoporous metals with other compositions and structures. When being performed for alkaline EOR electrocatalysis, the best PtRhPb MNSs deliver remarkably high activity (7.8 A mg-1) and superior C1 product selectivity (70% of Faradaic efficiency), both of which are much better than reported electrocatalysts. High performance is assigned to multiple structural and compositional synergies that not only stabilized key OHads intermediate by surface-clean mesopores but also separated the chemisorption of two carbons in ethanol by adjacent Pt and Rh sites, which facilitate the oxidation cleavage of stable C─C bond for complete EOR electrocatalysis.

Atomic Ru-Pt dual sites boost the mass activity and cycle life of alkaline hydrogen evolution

The development of highly efficient and ultrastable electrocatalysts for hydrogen generation from water/real seawater faces huge challenges. Herein, porous carbon-supported amorphous RuPt nanoclusters (Ru5.67Pt/PC) achieve mass activities of 42.28/10.93 A mgPt-1 and ultralong cycling stability in alkaline water/seawater because of the unique cluster structure and atomic Ru-Pt dual sites.

Electronic-Structure-Modulated Cu,Co-Coanchored N-Doped Nanocarbon as a Difunctional Electrocatalyst for Hydrogen Evolution and Oxygen Reduction Reactions

To alleviate the problems of environmental pollution and energy crisis, aggressive development of clean and alternative energy technologies, in particular, water splitting, metal-air batteries, and fuel cells involving two key half reactions comprising hydrogen evolution reaction (HER) and oxygen reduction (ORR), is crucial. In this work, an innovative hybrid comprising heterogeneous Cu/Co bimetallic nanoparticles homogeneously dispersed on a nitrogen-doped carbon layer (Cu/Co/NC) was constructed as a bifunctional electrocatalyst toward HER and ORR via a hydrothermal reaction along with post-solid-phase sintering technique. Thanks to the interfacial coupling and electronic synergism between the Cu and Co bimetallic nanoparticles, the Cu/Co/NC catalyst showed improved catalytic ORR activity with a half-wave potential of 0.865 V and an excellent stability of more than 30 h, even compared to 20 wt% Pt/C. The Cu/Co/NC catalyst also exhibited excellent HER catalytic performance with an overpotential of below 149 mV at 10 mA/cm2 and long-term operation for over 30 h.

CoO supported NiFe layered double hydroxide sandwich-like nanosheets on hierarchical carbon framework for efficient electrocatalytic oxygen evolution

Exploration of greatly efficient and steady non-noble oxygen evolution reaction (OER) electrocatalysts is of great significance in improving the overall efficiency of energy density systems such as regenerative fuel cells, water electrolyzes, and metal-air batteries. Herein, inspired by hierarchical 3D porous structures with open microchannels of natural wood, CoO@NiFe LDH sandwich-like nanosheets were anchored on the carbonized wood (CW) via electrodeposition and calcination strategies. The strong interactions between CoO nanosheets and NiFe LDH nanosheets endow CoO@NiFe LDH/CW electrocatalyst with high catalytic properties toward the OER comparable to CoO/CW and NiFe LDH/CW. The optimized CoO@NiFe LDH/CW electrocatalyst demonstrates good OER catalytic performance with an overpotential of 230 mV at 100 mA cm-2. This work presents an innovative approach to utilize renewable resources for constructing advanced free-standing catalysts.

Electrochemical Generation of Te Vacancy Pairs in PtTe for Efficient Hydrogen Evolution

Two-dimensional (2D) van der Waals materials are increasingly seen as potential catalysts due to their unique structures and unmatched properties. However, achieving precise synthesis of these remarkable materials and regulating their atomic and electronic structures at the most fundamental level to enhance their catalytic performance remain a significant challenge. In this study, we synthesized single-crystal bulk PtTe crystals via chemical vapor transport and subsequently produced atomically thin, large PtTe nanosheets (NSs) through electrochemical cathode intercalation. These NSs are characterized by a significant presence of Te vacancy pairs, leading to undercoordinated Pt atoms on their basal planes. Experimental and theoretical studies together reveal that Te vacancy pairs effectively optimize and enhance the electronic properties (such as charge distribution, density of states near the Fermi level, and d-band center) of the resultant undercoordinated Pt atoms. This optimization results in a significantly higher percentage of dangling O-H water, a decreased energy barrier for water dissociation, and an increased binding affinity of these Pt atoms to active hydrogen intermediates. Consequently, PtTe NSs featuring exposed and undercoordinated Pt atoms demonstrate outstanding electrocatalytic activity in hydrogen evolution reactions, significantly surpassing the performance of standard commercial Pt/C catalysts.

Atomic-Level Tailoring of the Electronic Metal-Support Interaction Between Pt-Co3O4 Interfaces for High Hydrogen Evolution Performance

Atomic-level modulation of the metal-oxide interface is considered an effective approach to optimize the electronic structure and catalytic activity of metal catalysts but remains highly challenging. Here, we employ the atomic layer deposition (ALD) technique together with a heteroatom doping strategy to effectively tailor the electronic metal-support interaction (EMSI) at the metal-oxide interface on the atomic level, thereby achieving high hydrogen evolution performance and Pt utilization. Theoretical calculations reveal that the doping of N atoms in Co3O4 significantly adjusts the EMSI between Pt-Co3O4 interfaces and, consequently, alters the d-band center of Pt and optimizes the adsorption/desorption of reaction intermediates. This work sheds light on the atomic-level regulation and mechanistic understanding of the EMSI in metal-oxide, while providing guidance for the development of advanced EMSI electrocatalysts for various future energy applications.

Mesoporous Mo-doped PtBi intermetallic metallene superstructures to enable the complete electrooxidation of ethylene glycol

Metallenes, intermetallic compounds, and porous nanocrystals are the three types of most promising advanced nanomaterials for practical fuel cell devices, but how to integrate the three structural features into a single nanocrystal remains a huge challenge. Herein, we report an efficient one-step method to construct freestanding mesoporous Mo-doped PtBi intermetallic metallene superstructures (denoted M-PtBiMo IMSs) as highly active and stable ethylene glycol oxidation reaction (EGOR) catalysts. The materials retained their catalytic performance, even in complex direct ethylene glycol fuel cells (DEGFCs). The M-PtBiMo IMSs showed EGOR mass and specific activities of 24.0 A mgPt-1 and 61.1 mA cm-2, respectively, which were both dramatically higher than those of benchmark Pt black and Pt/C. In situ infrared spectra showed that ethylene glycol underwent complete oxidation via a 10-electron CO-free pathway over the M-PtBiMo IMSs. Impressively, M-PtBiMo IMSs demonstrated a much higher power density (173.6 mW cm-2) and stability than Pt/C in DEGFCs. Density functional theory calculations revealed that oxophilic Mo species promoted the EGOR kinetics. This work provides new possibilities for designing advanced Pt-based nanomaterials to improve DEGFC performance.

In Situ Creation of Surface Defects on Pd@NiPd with Core-shell Hierarchical Structure Toward Boosting Electrocatalytic Activity

A deep insight into surface structural evolution of the catalyst is a challenging issue to reveal the structure-activity relationship. In this contribution, based on a surface alloying strategy, the dual-functional Pd@NiPd catalyst with a unique core-shell hierarchical structure is developed through selective crystal growth, surface cocrystallization, directional self-assembly, and reduction process. The surface defects are created in situ on the outer NiPd alloy layer in the electrochemical redox processes, which endow the Pd@NiPd catalyst with excellent electrocatalytic activity of hydrogen generation reaction (HER) and oxygen generation reaction (OER) in alkaline media. The optimal Pd@NiPd-2 catalyst requires an overpotential of only 18 mV that is far lower than Pt/C benchmark (43 mV) at the current density of 10 mA cm-2 for the HER, and 210 mV that is far lower than RuO2 benchmark (430 mV) at 50 mA cm-2 for the OER. Density functional theory (DFT) calculations reveal that the outstanding electrocatalytic activity is originated from the creation of surface defect structure that induces a significant reduction in the adsorption and dissociation energy barriers of H2O molecules in the HER and a decrease in the conversion energy from O* to OOH* that resulted from the synergy of two adjacent Pd sites by forming O-bridge. This work affords a typical paradigm for exploiting efficient catalysts and investigating the dependence of electrocatalytic activity on the surface structural evolution.