Highly Efficient Dehydrogenation of Formic Acid over a Palladium-Nanoparticle-Based Mott-Schottky Photocatalyst

Visible light-assisted hydrogen generation from ammonia borane over Z-Scheme NiO-CuO heterostructures

The design and fabrication of cheap and high-efficiency catalysts for ammonia borane (AB) hydrolysis for hydrogen production is crucial for its commercial applications. Improvement of the catalytic performance of the catalysts with the assistance of sunlight, a costless resource, is extremely attractive. Herein, we have constructed Z-scheme heterostructured VO-NiO-CuO catalysts with strong interfacial electronic interactions and abundant oxygen vacancies to enhance hydrogen production from NH3BH3 solution under visible light illumination. The as-prepared VO-NiO-CuO catalysts exhibit excellent catalytic activity with a high turnover frequency (TOF) of 35.3 molH2 molcat.-1 min-1 toward AB hydrolysis under visible light. It is demonstrated that excellent catalytic performance is highly related to the effective separation and migration of charge on the catalyst surface. As a result, dual active sites were created, making it easier for various reactants to be adsorbed and activated on the catalyst surface. Furthermore, the density functional theory (DFT) calculations indicate that the adsorption and activation of H2O occurred mainly at the Ni site of VO-NiO-CuO. When the VO-NiO-CuO is irradiated with visible light, the photogenerated electrons assembled on the conduction band were transferred to the O atom through the Ni-O bond, which made the bond length of H2O molecules longer and OH bonds more prone to breaking, thus facilitating AB hydrolysis under illumination. The findings in this work pave the way to design novel and efficient heterostructured catalysts for fast hydrogen release from NH3BH3 under visible light irradiation.

Enhancing Photocatalytic-Transfer Semi-Hydrogenation of Alkynes Over Pd/C3 N4 Through Dual Regulation of Nitrogen Defects and the Mott-Schottky Effect

The selective hydrogenation of alkynes is an important reaction; however, the catalytic activity and selectivity in this reaction are generally conflicting. In this study, ultrafine Pd nanoparticles (NPs) loaded on a graphite-like C3 N4 structure with nitrogen defects (Pd/DCN) are synthesized. The resulting Pd/DCN exhibits excellent photocatalytic performance in the transfer hydrogenation of alkynes with ammonia borane. The reaction rate and selectivity of Pd/DCN are superior to those of Pd/BCN (bulk C3 N4 without nitrogen defects) under visible-light irradiation. The characterization results and density functional theory calculations show that the Mott-Schottky effect in Pd/DCN can change the electronic density of the Pd NPs, and thus enhances the hydrogenation selectivity toward phenylacetylene. After 1 h, the hydrogenation selectivity of Pd/DCN reaches 95%, surpassing that of Pd/BCN (83%). Meanwhile, nitrogen defects in the supports improve the visible-light response and accelerate the transfer and separation of photogenerated charges to enhance the catalytic activity of Pd/DCN. Therefore, Pd/DCN exhibits higher efficiency under visible light, with a turnover frequency (TOF) of 2002 min-1 . This TOF is five times that of Pd/DCN under dark conditions and 1.5 times that of Pd/BCN. This study provides new insights into the rational design of high-performance photocatalytic transfer hydrogenation catalysts.

Design of the Synergistic Rectifying Interfaces in Mott-Schottky Catalysts

The functions of interfacial synergy in heterojunction catalysts are diverse and powerful, providing a route to solve many difficulties in energy conversion and organic synthesis. Among heterojunction-based catalysts, the Mott-Schottky catalysts composed of a metal-semiconductor heterojunction with predictable and designable interfacial synergy are rising stars of next-generation catalysts. We review the concept of Mott-Schottky catalysts and discuss their applications in various realms of catalysis. In particular, the design of a Mott-Schottky catalyst provides a feasible strategy to boost energy conversion and chemical synthesis processes, even allowing realization of novel catalytic functions such as enhanced redox activity, Lewis acid-base pairs, and electron donor-acceptor couples for dealing with the current problems in catalysis for energy conversion and storage. This review focuses on the synthesis, assembly, and characterization of Schottky heterojunctions for photocatalysis, electrocatalysis, and organic synthesis. The proposed design principles, including the importance of constructing stable and clean interfaces, tuning work function differences, and preparing exposable interfacial structures for designing electronic interfaces, will provide a reference for the development of all heterojunction-type catalysts, electrodes, energy conversion/storage devices, and even super absorbers, which are currently topics of interest in fields such as electrocatalysis, fuel cells, CO₂ reduction, and wastewater treatment.

High performance recycled CFRP composites based on reused carbon fabrics through sustainable mild solvolysis route

A novel environmentally friendly recycling method is developed for large carbon-fibers reinforced-polymers composite panels whose efficiency is demonstrated through a proof-of-concept fabrication of a new composite part based on recycled fibers. The recycling process relies on formic acid as separation reagent at room temperature and atmospheric pressure with efficient recycling potential of the separating agent. Electron microscopy and thermal analysis indicate that the recycled fibers are covered by a thin layer of about 10wt.% of residual resin, alternating with few small particles, as compared to the smooth virgin fibers. The recycled composites show promising shear strength and compression after impact strength, with up to 93% retention of performance depending on the property as compared to the reference. The recycled carbon fibers can thus be reused for structural applications requiring moderate to high performances. The loss of properties is attributed to a lower adhesion between fresh epoxy resin and recycled carbon fibers due to the absence of sizing, partly compensated by a good interface between fresh and residual cured epoxy thanks to mechanical anchoring as well as chemical reactions. The room temperature and atmospheric pressure operating conditions combined to the recyclability of the forming acid contribute to the sustainability of the entire approach.

Constructing Schottky junctions via Pd nanosheets on DUT-67 surfaces to accelerate charge transfer

The separation, transfer and recombination of charge often affect the rate of photocatalytic reduction of CO₂. Schottky junctions can promote the rapid separation of space charge. Therefore, in this paper, Pd nanosheets were grown on the surface of DUT-67 by a hydrothermal method, and a Schottky junction was constructed between DUT-67 and Pd. Under the action of the Schottky junction, the CO yield of 0.3-Pd/DUT-67 reached 12.15 μmol/g/h, which was 17 times higher than that of DUT-67. Efficient charge transfer was demonstrated in photochemical experiments. The large specific surface area and the increased light utilization rate also contributed to the increase in the CO₂ reduction efficiency. In addition, the mechanism of Pd/DUT-67 photocatalytic reduction of CO₂ was proposed.

Facet-engineering palladium nanocrystals for remarkable photocatalytic dechlorination of polychlorinated biphenyls

Rationally constructing functionalized cocatalysts for removing chemically inert polychlorinated biphenyls is significant and challenging.

Prolonged-Photoresponse-Lifetime Ni2P Nanocrystalline with Highly Exposed (001) for Efficient Photoelectrocatalytic Hydrogen Evolution

Seeking highly efficient non-preference electrocatalytic materials that serve photoelectrochemical (PEC) water splitting in acidic systems is expectant in the context of environmentally friendly production. We designed Ni₂P electrocatalysts synthesized in oil phases via the hot-bubbling method with superb stability in air and sulfuric acid solution for PEC, which were found with excellent hydrogen evolution performance. A tunable particle size and highly exposed (001) planes of Ni₂P nanocrystals were achieved. The designed catalysts achieved a notable promotion in the hydrogen evolution reaction activity compared to that of Ni₂P synthesized in the water phase. More specifically, the electrode prepared by self-assembled Ni₂P nanoparticles was found to have decent over-potential of η₁₀ = 164 mV in darkness and was further decreased to 129 mV with irradiation of visible light. The cyclic stability tests manifested brilliant durability in 0.5 M H₂SO₄. Measurement of the transient photocurrent response and PEC water splitting catalytic performance indicated that the Ni₂P had high carrier concentration upon irradiation, lower carrier recombination probability, and prolonged photo-response lifetime (3.03-3.14 s).

H2 Production from Formic Acid Using Highly Stable Carbon-Supported Pd-Based Catalysts Derived from Soft-Biomass Residues: Effect of Heat Treatment and Functionalization of the Carbon Support

The production of hydrogen from liquid organic hydrogen carrier molecules stands up as a promising option over the conventional hydrogen storage methods. In this study, we explore the potential of formic acid as a convenient hydrogen carrier. For that, soft-biomass-derived carbon-supported Pd catalysts were synthesized by a H₃PO₄-assisted hydrothermal carbonization method. To assess the impact of the properties of the support in the catalytic performance towards the dehydrogenation of formic acid, three different strategies were employed: (i) incorporation of nitrogen functional groups; (ii) modification of the surface chemistry by performing a thermal treatment at high temperatures (i.e., 900 °C); and (iii) combination on both thermal treatment and nitrogen functionalization. It was observed that the modification of the carbon support with these strategies resulted in catalysts with enhanced performance and outstanding stability even after six consecutive reaction cycles, thus highlighting the important effect of tailoring the properties of the support.

Highly Efficient Dehydrogenation of Formic Acid over Binary Palladium-Phosphorous Alloy Nanoclusters on N-Doped Carbon

Highly efficient dehydrogenation of formic acid (FA) at room temperature is a safe and suitable way to obtain hydrogen and promote the development of hydrogen storage application. Herein, the phosphorous-alloyed Pd nanoclusters loading on nitrogen-doped carbon (PdP/NC) were prepared and recognized as the highly active nanocatalysts for the dehydrogenation of FA. The PdP/NCs with controlled sizes and compositions were prepared by an easy self-limiting synthesis in an aqueous solution. The best PdP/NC exhibited a remarkable catalytic activity with a high turnover frequency of ∼3253.0 h^-1 than the compared nanocatalysts for the dehydrogenation of FA at room temperature. The catalytic kinetics and durability studies showed that both the alloyed P in Pd crystals and doped N in the carbon support could effectively tailor the electronic states of the Pd surface and further optimize the adsorption energy of FA. Based on the Sabatier principle, the proper adsorption energy accelerated the dehydrogenation reaction and correspondingly enhanced the activity and durability. The work proposed a high-efficiency nanocatalyst for safe hydrogen generation and may be extended to create other similar nanocatalysts with different compositions and nanostructures.

Optimizing the metal-support interactions at the Pd-polymer carbon nitride Mott-Schottky heterojunction interface for an enhanced electrocatalytic hydrodechlorination reaction

We reported one novel strategy via band engineering of the semiconductor support to optimize the metal-support interactions at a Mott-Schottky heterojunction interface and enhance the metal's electrocatalytic hydrodechlorination (EHDC) performance. Taking palladium-polymer carbon nitride (Pd/PCN) as a model, the band tuning of PCN by heteroatomic phosphorus (P) doping substantially boosted the EHDC of 2,4-dichlorophenol (2,4-DCP, one typical chlorinated organic pollutants (COPs)) on Pd, and a peak specific activity of 0.172 min^-1 cm_Pd^-2 was achieved by Pd/P-PCN-0.25 (0.25 reflected the P content, and denoted the mass ratio of the P source to PCN precursor used in P-PCN synthesis), quadrupling 0.041 min^-1 cm_Pd^-2 of Pd/C and outperforming most of the reported catalysts. The mechanism study revealed the P doping in PCN enabled the positive shift of its Fermi level, which weakened the Pd-PCN interactions and alleviated the electron excess of Pd in Pd/PCN. The P-PCN in Pd/P-PCN-0.25 with the ideal band structure evoked a Pd electronic state that maximized EHDC efficiency. Further investigation into the intermediate products of EHDC on Pd/P-PCN and the biological safety of the 2,4-DCP-contaminated water after EHDC treatment demonstrated the EHDC over our catalyst was environmental-benignity for COPs abatement.

CdS Nanorods Anchored with Crystalline FeP Nanoparticles for Efficient Photocatalytic Formic Acid Dehydrogenation

Photocatalytic dehydrogenation of formic acid is a promising strategy for H₂ generation. In this work, we report the use of crystalline iron phosphide (FeP) nanoparticles as an efficient and robust cocatalyst on CdS nanorods (FeP@CdS) for highly efficient photocatalytic formic acid dehydrogenation. The optimal H₂ evolution rate can reach ∼556 μmol·h^-1 at pH 3.5, which is more than 37 times higher than that of bare CdS. Moreover, the photocatalyst demonstrates excellent stability; no significant decrease of the catalytic activity was observed during continuous testing for more than four days. The apparent quantum yield is ∼54% at 420 nm, which is among the highest values obtained using noble-metal-free photocatalysts for formic acid dehydrogenation. This work provides a novel strategy for designing highly efficient and economically viable photocatalysts for formic acid dehydrogenation.

LC-MS analysis of nitroguanidine compounds by catalytic reduction using palladium modified graphitic carbon nitride catalyst

The analysis of compounds of the nitroguanidine family at trace level poses an analytical challenge. Nitroguanidine, 1-methyl-3-nitroguanidine, and 1-methyl-3-nitro-1-nitrosoguanidine, which are addressed in this article, have low lipophilicity, with log(K_ow) equal to -0.89, - 0.84, and 0.68, respectively, and as such are not amenable for preconcentration from water. Liquid-liquid extraction and SPE fail to concentrate them from water and it is also not possible to extract them by ion exchange resin even after a pH change. Nitroguanidine and 1-methyl-3-nitroguanidine nitramines are explosives of growing use and thereby growing environmental concern due to lower detonation sensitivity compared to RDX. A sensitive method for the determination of nitroguanidine, 1-methyl-3-nitroguanidine, and 1-methyl-3-nitroso-1-nitroguanidine by reduction to the respective amines and subsequent hydrophobization by derivatization with 4-nitrobenzaldehyde followed by LC-ESI-MS analysis is described. Reduction by sodium borohydride using palladium modified graphitic carbon nitride (Pd/g-C₃N₄) provided improved sensitivity compared to the traditional palladium modified activated carbon due to the lower adsorption of the reduction products on the carbon nitride substrate. The limit of detection of the method was 10 ng L^-1 for nitroguanidine, and repeated analyses of spiked effluents and contaminated spring water gave relative standard deviations of 8.8% and 6.5%, respectively. The findings illuminate the great promise of Pd/g-C₃N₄ as a reduction catalyst for the determination of challenging hydrophilic organic contaminants.

Copper-free Sonogashira cross-coupling reactions: an overview

The Sonogashira reaction is a cross-coupling reaction of a vinyl or aryl halide with a terminal alkyne to form a C-C bond. In its original form, the Sonogashira reaction is performed with a palladium species as a catalyst while co-catalyzed by a copper species and a phosphine or amine. The reaction is conducted under mild conditions, i.e., room temperature, aqueous solutions, and the presence of mild bases. Undeniably, the Sonogashira reaction is among the most competent and efficient reactions widely used in organic synthesis. This named reaction has proved useful in many organic synthesis areas, including the synthesis of pharmaceuticals, heterocycles, natural products, organic compounds, complex molecules having biological activities, nanomaterials, and many more materials that we use in our daily lives. The presence of transition metals as a catalyst was indeed essential in the Sonogashira reaction. However, recently, the reaction has been successfully conducted without copper as a co-catalyst and phosphines or amines as bases. In this critical review, we have focused on developments in the Sonogashira reaction successfully performed in the absence of copper complexes, phosphines or amines, which could be of particular advantage in implementing green chemistry principles and making the reactions more achievable from an economic viewpoint.

Activating Co nanoparticles on graphitic carbon nitride by tuning the Schottky barrier via P doping for the efficient dehydrogenation of ammonia-borane

A highly active Mott–Schottky nanocatalyst for the efficient dehydrogenation of ammonia-borane was constructed by rationally tuning the Schottky barrier of Co/P_xCN (P-doped g-C₃N₄) via simply varying the doping amount of P atoms.

Nanopore-Supported Metal Nanocatalysts for Efficient Hydrogen Generation from Liquid-Phase Chemical Hydrogen Storage Materials

Hydrogen has emerged as an environmentally attractive fuel and a promising energy carrier for future applications to meet the ever-increasing energy challenges. The safe and efficient storage and release of hydrogen remain a bottleneck for realizing the upcoming hydrogen economy. Hydrogen storage based on liquid-phase chemical hydrogen storage materials is one of the most promising hydrogen storage techniques, which offers considerable potential for large-scale practical applications for its excellent safety, great convenience, and high efficiency. Recently, nanopore-supported metal nanocatalysts have stood out remarkably in boosting the field of liquid-phase chemical hydrogen storage. Herein, the latest research progress in catalytic hydrogen production is summarized, from liquid-phase chemical hydrogen storage materials, such as formic acid, ammonia borane, hydrous hydrazine, and sodium borohydride, by using metal nanocatalysts confined within diverse nanoporous materials, such as metal-organic frameworks, porous carbons, zeolites, mesoporous silica, and porous organic polymers. The state-of-the-art synthetic strategies and advanced characterizations for these nanocatalysts, as well as their catalytic performances in hydrogen generation, are presented. The limitation of each hydrogen storage system and future challenges and opportunities on this subject are also discussed. References in related fields are provided, and more developments and applications to achieve hydrogen energy will be inspired.

Anchoring Pd-nanoparticles on dithiocarbamate- functionalized SBA-15 for hydrogen generation from formic acid

Hydrogen (H₂) generation from natural biological metabolic products has remained a huge challenge for the energy arena. However, designing a catalytic system with complementary properties including high surface area, high loading, and easy separation offers a promising route for efficient utilization of nanoreactors for prospective H₂ suppliers to a fuel cell. Herein, selective dehydrogenation of formic acid (FA) as a natural biological metabolic product to H₂ and CO₂ gas mixtures has been studied by supporting ultrafine palladium nanoparticles on organosulfur-functionalized SBA-15 nanoreactor under ultrasonic irradiation. The effects of the porous structure as a nanoreactor, and organosulfur groups, which presented around the Pd due to their prominent roles in anchoring and stabilizing of Pd NPs, studied as a superior catalyst for selective dehydrogenation of FA. Whole catalytic systems were utilized in ultrasonic irradiation in the absence of additives to provide excellent TOF/TON values. It was found that propose catalyst is a greener, recyclable, and more suitable option for the large-scale application and provide some new insights into stabilization of ultra-fine metal nanoparticle for a variety of applications.

Activating palladium nanoparticles via a Mott-Schottky heterojunction in electrocatalytic hydrodechlorination reaction

This work exploited one novel power of the Mott-Schottky heterojunction interface in activating the palladium (Pd) in electrocatalytic hydrodechlorination reaction (EHDC, one reaction targeted for the abatement of chlorinated organic pollutants from water). By forming a Mott-Schottky contact with polymer carbon nitride (Pd-PCN), the Pd nanoparticles enable a relatively complete and pseudo-first-order conversion of 2,4-dichlorophenol (2,4-DCP) to phenol and Cl^- with the reaction rate constant (k_obs) triple that of the conventional Pd-C (0.68 vs. 0.26 min^-1 mol_Pd^-1). Further comparison in k_obs of Pd-PCN and the Pd catalysts reported in literatures revealed that our Pd-PCN was among the top active catalysts for EHDC. The robust performance of Pd-PCN was attributed to the strong metal-support interactions at the Mott-Schottky heterojunction interface, which enriched the electron on Pd and improved its anti-poisoning ability against phenol. The strong support-metal interactions also endowed Pd-PCN with high activity/structure stability in EHDC. The presence of some anions in water body including NO₃^-, NO₂^- and Cl^- exerted little effect on EHDC, while the reduced sulfur compounds (S^2- and SO₃^2-), even in a very low concentration (1 mM), could significantly deactivate the catalyst. This work provides a facile and efficient strategy to activate noble metals in catalytic reactions.

Mild and selective hydrogenation of CO2 into formic acid over electron-rich MoC nanocatalysts

The direct hydrogenation of CO₂ using H₂ gas is a one-stone-two-birds route to produce highly value-added hydrocarbon compounds and to lower the CO₂ level in the atmosphere. However, the transformation of CO₂ and H₂ into hydrocarbons has always been a great challenge while ensuring both the activity and selectivity over abundant-element-based nanocatalysts. In this work, we designed a Schottky heterojunction composed of electron-rich MoC nanoparticles embedded inside an optimized nitrogen-doped carbon support (MoC@NC) as the first example of noble-metal-free heterogeneous catalysts to boost the activity of and specific selectivity for CO₂ hydrogenation to formic acid (FA) in liquid phase under mild conditions (2 MPa pressure and 70 °C). The MoC@NC catalyst with a high turnover frequency (TOF) of 8.20 mol_FA mol_MoC^-1 h^-1 at 140 °C and an excellent reusability are more favorable for real applications.

Cellulose as an Inert Scaffold in Plasmon-Assisted Photoregeneration of Cofactor Molecules

Plasmonic nanoparticles exhibit excellent light-harvesting properties in the visible spectral range, which makes them a convenient material for the conversion of light into useful chemical fuel. However, the need for using surface ligands to ensure colloidal stability of nanoparticles inhibits their photochemical performance due to the insulating molecular shell hindering the carrier transport. We show that cellulose fibers, abundant in chemical functional groups, can serve as a robust substrate for the immobilization of gold nanorods, thus also providing a facile way to remove the surfactant molecules. The resulting functional composite was implemented in a bioinspired photocatalytic process involving dehydrogenation of sodium formate and simultaneous photoregeneration of cofactor molecules (NADH, nicotinamide adenine dinucleotide) using visible light as an energy source. By systematic screening of experimental parameters, we compare photocatalytic and thermocatalytic properties of the composite and evaluate the role of palladium cocatalyst.

Metal-organic frameworks derived carbon-incorporated cobalt/dicobalt phosphide microspheres as Mott-Schottky electrocatalyst for efficient and stable hydrogen evolution reaction in wide-pH environment

Cobalt phosphides, as low cost and abundant non-noble materials for hydrogen evolution reaction (HER), are always constrained by their inferior charge transfer and sluggish intrinsic electrocatalytic kinetics. In this work, carbon-incorporated Co/Co₂P microspheres (Co/Co₂P@C) as a novel Mott-Schottky catalyst were synthesized successfully via carbonization and gradual phosphorization of Co based metal-organic frameworks. The unique merits, including Mott-Schottky effect at the interface formed between metal Co and semiconductor Co₂P, the incorporated carbon-layer on the surface and the spherical structure endow Co/Co₂P@C with favorable electrical conductivity, preferable kinetics and long-term stability when it was evaluated as electrocatalyst for HER in wide-pH range. As a result, the Co/Co₂P@C with the optimized phosphorization degree delivers a benchmark current density of 10 mA cm^-2 at the low overpotential of 192 and 158 mV in acidic and alkaline electrolytes, respectively, with a remarkable stability (CV cycling for 3000 cycles and continuous electrolysis at the overpotential of 200 mV for 48 h). Therefore, the as-designed Co/Co₂P@C should be one of the most promising catalysts for HER application.

Atomically Dispersed Co-P3 on CdS Nanorods with Electron-Rich Feature Boosts Photocatalysis

The development of highly efficient photocatalytic systems with rapid photogenerated charge separation and high surface catalytic activity is highly desirable for the storage and conversion of solar energy, yet remains a grand challenge. Herein, a conceptionally new form of atomically dispersed Co-P₃ species on CdS nanorods (CoPSA-CdS) is designed and synthesized for achieving unprecedented photocatalytic activity for the dehydrogenation of formic acid (FA) to hydrogen. X-ray absorption near edge structure, X-ray photoelectron spectroscopy, and time-resolved photoluminescence results confirm that the Co-P₃ species have a unique electron-rich feature, greatly improving the efficiency of photogenerated charge separation through an interface charge effect. The in situ attenuated total reflection infrared spectra reveal that the Co-P₃ species can achieve much better dissociation adsorption of FA and activation of CH bonds than traditional sulfur-coordinated Co single atom-loaded CdS nanorods (CoSSA-CdS). These two new features make CoPSA-CdS exhibit the unprecedented 50-fold higher activity in the photocatalytic dehydrogenation of FA than CoSSA-CdS, and also much better activity than the Ru-, Rh-, Pd-, or Pt-loaded CdS. Besides, CoPSA-CdS also shows the highest mass activity (34309 mmol g_Co ^-1 h^-1 ) of Co reported to date. First-principles simulation reveals that the Co-P₃ species herein can form an active PHCOO intermediate for enhancing the rate-determining dissociation adsorption of FA.

Ultrafine PdAg nanoparticles immobilized on nitrogen-doped carbon/cerium oxide for superior dehydrogenation of formic acid

Ultrafine PdAg NPs with the size of 2.5 nm are successfully immobilized on cerium oxide/nitrogen-doped carbon.

Promoting the hydrogenation of acetone C–C coupling into pinacol with dehydrogenation of formic acid over a NaOH-treated g-C3N4 photocatalyst

NaOH-treated g-C₃N₄ photocatalytic dehydrogenation of formic acid to promote the hydrogenation of acetone C–C coupling into pinacol was carried out in which photo-electrons and photo-holes were effectively used.

Palladium nanoparticles supported on nanosheet-like graphitic carbon nitride for catalytic transfer hydrogenation reaction

Pd/g-C₃N₄ catalysts with well-dispersed, electron-enriched Pd nanoparticles immobilized on pyridinic N atoms of g-C₃N₄ are active for catalytic transfer hydrogenation under ambient conditions.

Promoting Pt catalysis for CO oxidation via the Mott-Schottky effect

CO oxidation is an important reaction both experimentally and industrially, and its performance is usually dominated by the charge states of catalysts. For example, CO oxidation on the platinum (Pt) surface requires a properly charged state for the balance of adsorption and activation of CO and O₂. Here, we present "Mott-Schottky modulated catalysis" on Pt nanoparticles (NPs) via an electron-donating carbon nitride (CN) support with a tunable Fermi level. We demonstrate that properly-charged Pt presents an excellent catalytic CO oxidation activity with an initial conversion temperature as low as 25 °C and total CO conversion below 85 °C. The tunable electronic structure of Pt NPs, which is regulated by the Fermi level of CN, is a key factor in dominating the catalytic performance. This "Mott-Schottky modulated catalysis" concept may be extended to maneuver the charge state on other metal catalysts for targeted catalytic reactions.

Boosting selective nitrogen reduction to ammonia on electron-deficient copper nanoparticles

Production of ammonia is currently realized by the Haber–Bosch process, while electrochemical N₂ fixation under ambient conditions is recognized as a promising green substitution in the near future. A lack of efficient electrocatalysts remains the primary hurdle for the initiation of potential electrocatalytic synthesis of ammonia. For cheaper metals, such as copper, limited progress has been made to date. In this work, we boost the N₂ reduction reaction catalytic activity of Cu nanoparticles, which originally exhibited negligible N₂ reduction reaction activity, via a local electron depletion effect. The electron-deficient Cu nanoparticles are brought in a Schottky rectifying contact with a polyimide support which retards the hydrogen evolution reaction process in basic electrolytes and facilitates the electrochemical N₂ reduction reaction process under ambient aqueous conditions. This strategy of inducing electron deficiency provides new insight into the rational design of inexpensive N₂ reduction reaction catalysts with high selectivity and activity.

Electrocatalytic nitrogen reduction is promising for ammonia production, but electrocatalysts are limited by low efficiency and high cost. Here, the authors report electron-deficient copper nanoparticles, induced by rectifying contact with polyimide, for selective reduction of nitrogen to ammonia.