Hydrogenation Activity Research Articles

Regulating Interfacial Hydrogen‐Bonding Networks by Implanting Cu Sites with Perfluorooctane to Accelerate CO2 Electroreduction to Ethanol

Efficient CO2 electroreduction (CO2RR) to ethanol holds promise to generate value‐added chemicals and harness renewable energy simultaneously. Yet, it remains an ongoing challenge due to the competition with thermodynamically more preferred ethylene production. Herein, we presented a CO2 reduction predilection switch from ethylene to ethanol (ethanol‐to‐ethylene ratio of ~5.4) by inherently implanting Cu sites with perfluorooctane to create interfacial non‐covalent interactions. The 1.83%F‐Cu2O organic‐inorganic hybrids (OIHs) exhibited an extraordinary ethanol faradaic efficiency (FEethanol) of ∼55.2%, with an impressive ethanol partial current density of 166 mA cm‐2 and excellent robustness over 60 hours of continuous operation. This exceptional performance ranks our 1.83%F‐Cu2O OIHs among the best‐performing ethanol‐oriented CO2RR electrocatalysts. Our findings identified that C8F18 could strengthen the interfacial hydrogen bonding connectivity, which consequently promotes the generation of active hydrogen species and preferentially favors the hydrogenation of *CHCOH to *CHCHOH, thus switching the reaction from ethylene‐preferred to ethanol‐oriented. The presented investigations highlight opportunities for using noncovalent interactions to tune the selectivity of CO2 electroreduction to ethanol, bringing it closer to practical implementation requirements.

Surface Structure Dependent Activation of Hydrogen over Metal Oxides during Syngas Conversion.

Despite the extensive studies on the adsorption and activation of hydrogen over metal oxides, it remains a challenge to investigate the structure-dependent activation of hydrogen and its selectivity mechanism in hydrogenation reactions. Herein we take spinel and solid solution MnGaOx with a similar bulk chemical composition and study the hydrogen activation mechanism and reactivity in syngas conversion. The results show that MnGaOx-Solid Solution (MnGaOx-SS) is a typical Mn-doped hexagonal close-packed (HCP) Ga2O3 with a Ga-rich surface. Upon exposure to hydrogen, Ga-H and O-H species are simultaneously generated. Ga-H species are highly active but unselective in CO activation, forming CHxO, and ethylene hydrogenation, forming ethane. In contrast, MnGaOx-Spinel is a face-centered-cubic (FCC) spinel phase featuring a Mn-rich surface, thus effectively suppressing the formation of Ga-H species. Interestingly, only part of the O-H species are active for CO activation while the O-H species are inert for olefin hydrogenation over MnGaOx-Spinel. Therefore, MnGaOx-Spinel exhibits a higher activity and higher light-olefin selectivity than MnGaOx-SS in combination with SAPO-18 during syngas conversion. These fundamental understandings are essential to guide the design and further optimization of metal oxide catalysts for selectivity control in hydrogenations.

Regulating Interfacial Hydrogen-Bonding Networks by Implanting Cu Sites with Perfluorooctane to Accelerate CO2 Electroreduction to Ethanol.

Efficient CO2 electroreduction (CO2RR) to ethanol holds promise to generate value-added chemicals and harness renewable energy simultaneously. Yet, it remains an ongoing challenge due to the competition with thermodynamically more preferred ethylene production. Herein, we presented a CO2 reduction predilection switch from ethylene to ethanol (ethanol-to-ethylene ratio of ~5.4) by inherently implanting Cu sites with perfluorooctane to create interfacial non-covalent interactions. The 1.83%F-Cu2O organic-inorganic hybrids (OIHs) exhibited an extraordinary ethanol faradaic efficiency (FEethanol) of ∼55.2%, with an impressive ethanol partial current density of 166 mA cm-2 and excellent robustness over 60 hours of continuous operation. This exceptional performance ranks our 1.83%F-Cu2O OIHs among the best-performing ethanol-oriented CO2RR electrocatalysts. Our findings identified that C8F18 could strengthen the interfacial hydrogen bonding connectivity, which consequently promotes the generation of active hydrogen species and preferentially favors the hydrogenation of *CHCOH to *CHCHOH, thus switching the reaction from ethylene-preferred to ethanol-oriented. The presented investigations highlight opportunities for using noncovalent interactions to tune the selectivity of CO2 electroreduction to ethanol, bringing it closer to practical implementation requirements.

Direct synthesis of liquid hydrocarbons from CO2 and H2 over bifunctional ZnCrOx-НZSM-5 combined and composite catalysts in a single reactor

A one-stage synthesis of gasoline fraction from CO2 and H2 was carried out on Zn-Cr–oxide-zeolite combined and composite catalysts. It was found that after oxidative and reduction treatment the catalysts contain ZnO and ZnCr2O4 phases. The one-step coprecipitation of zinc and chromium salts in the presence of zeolite allows obtaining an active bifunctional composite catalyst, each particle of which contains Zn-Cr oxide and zeolite components. A synergistic catalysis due to a closer distance of metal and acid sites increased the efficiency of such a catalyst in CO2 hydrogenation. It was found that the optimal temperature of oxidative activation of the composite catalyst is 400 ° C. With an increase in the temperature of oxidative treatment of the composite catalyst from 400 to 500°C, part of the zinc leaves the structure of the non-stoichiometric spinel and leads to a decrease in the basicity of the catalyst, which is responsible for the activation of CO2 on surface oxygen vacancies. Agglomerated ZnO particles blocked the pores and reduced their volume, as well as the specific surface of the catalyst. At the same time, the total acidity of the catalyst decreased. ZnO-species, which have hydrogenating activity, under the reaction conditions removed alkenes from the reaction cycle and thereby reduced the C5+–selectivity of the composite catalyst. Among the studied catalysts, the ZnCrOx-НZSM-5/Al2O3(400) composite catalyst in the tail-gas recirculation mode at 380°C and 10 MPa demonstrated high CO2 conversion of 25% and high selectivity for C5+–HCs of 53 wt% with a high content of isoalkanes 71 wt% for 60 hours. The methane content in the tail-gas did not exceed 3 vol%. The results obtained will be used to develop approaches to creating effective catalysts for the one-stage CO2 hydrogenation into valuable petrochemical products.

Enhanced conversion of rosin to polymerized rosin with reusable Brønsted acid deep eutectic solvent

With the depletion of non-renewable resources and the increasingly serious environmental problems, the production of high value-added polymer materials using renewable resources as raw materials had aroused great interest. Deep eutectic solvent (DES)-[ChCl][TfOH]2 (prepared by choline chloride (ChCl) and trifluoromethanesulfonic acid (TfOH)), with suitable acid strength (H0=0.98) and active hydrogen, had been successfully used for enhanced conversion of rosin to polymerized rosin efficiently, under the conditions of rosin =15 g, mDES: mrosin=30 %, T=110℃ and t=9 h, polymerized rosin with high softening point (150.40℃) and low acid value (124.21 mg KOH/g) could be produced efficiently. [ChCl][TfOH]2 required no special treatment then could be reused for 5 times without significant loss of catalytic performance, on this basis, the green synthesis technology of polymerized rosin under DES system was given, not only promoted the further application of polymerized rosin, but also realized the high value-added utilization of renewable resource rosin. In addition, the formation mechanism of DES was systematically explained through DFT calculation, the reaction mechanism of rosin polymerization over [ChCl][TfOH]2 was explored, which could provide theoretical basis for further research.

Synergistic regulation of dual thresholds: Hydroxyl occupancy and carbon species in the targeted catalytic hydrocracking of lignite

The preparation of carbon-based catalyst supports from low-grade lignite, followed by its self-catalytic hydrocracking to produce lignite-derived aromatic compounds, is crucial for achieving efficient lignite utilization and expanding aromatic compound sources. During lignite catalytic hydrocracking, the uncontrolled diffusive migration of active hydrogen (H*) and insufficient protection of aromatic rings reduce the yield of aromatic compounds. Using Heishan lignite as the raw material, we employed a relay process of thermal-induced self-assembly and oxidation-mediated carbon distortion for fabricating the Co3O4/AC&GC-S-600 composite material, which features an optimal hydroxyl occupancy ratio and a balanced combination of amorphous carbon/graphite carbon (AC/GC) types. The optimal hydroxyl occupancy threshold balances Co3O4 dispersion and hydrophilicity, facilitating the efficient formation and directional migration of H* through synergistic interaction between Co3O4 and H2O. The adequate threshold of AC/GC ratio regulates substrate adsorption, activation, and inhibition of aromatic hydrogenation, enhancing selective C–O bridge bond cleavage and preserving the unsaturation of aromatic rings. The synergistic regulation of dual thresholds promotes the rapid formation and the directional migration of H*, enabling efficient conversion of Heishan lignite to aromatic compounds (45.8% conversion, 80.8% selectivity) under mild conditions. Characterization techniques, experimental analyses, kinetic studies, and density functional theory calculations confirm that thermally induced self-assembly and oxidation-mediated carbon distortion are crucial for redistributing the carbon framework of the Heishan lignite matrix and regulating the optimal dual thresholds of hydroxyl occupancy and AC/GC types, which are essential for the catalytic hydrocracking of Heishan lignite to aromatic compounds. This strategy provides a scientific basis for selective catalytic production of lignite-based aromatic compounds, thereby supporting its clean and efficient utilization.

Advancing equitable value chains for the global hydrogen economy

Hydrogen is a rapidly growing focus for countries seeking to develop green industries, but there are many questions about how the nascent global hydrogen economy will develop, and what this implies for equitable sharing of benefits and burdens between nations. In this perspective we summarize emerging trends in national hydrogen strategies and develop recommendations for researchers and policymakers to center equity in hydrogen development. This will require integrating innovation and development perspectives on international technology transfer, developing more detailed representation of hydrogen trade in systems models, building equity considerations into national and international planning processes, and establishing robust technology transfer efforts. Policymakers will also need to grapple with the difficulties of verifying life cycle emissions of hydrogen if hydrogen trade emerges as a significant trend, potentially requiring new methods of emissions accounting and trade reforms that prioritize international equity.

Enhanced photocatalytic hydrogen and oxygen evolution activity by two-dimensional van der Waals AlSb/ZnO heterostructure: A first-principles study

Photocatalytic water splitting facilitates the generation of green hydrogen energy by transforming renewable solar energy into chemical energy. This paper investigated the electronic, optical, and photocatalytic properties of AlSb/ZnO van der Waals (vDW) heterostructure using density functional theory. AlSb/ZnO, a semiconductor heterostructure with an indirect bandgap, was energetically stable with a formation energy of −0.4 eV as well as dynamically and thermally stable. The band edges of the 2D heterostructure maintained the essential redox energy levels for complete water splitting, allowing hydrogen and oxygen generation. Moreover, the heterostructure exhibited a high absorption coefficient in the visible region of the solar spectrum compared to the individual AlSb and ZnO monolayers. We revealed low barrier potential at neutral pH conditions for oxygen and hydrogen evolution reactions from the Gibbs free energy calculation without any external potential. Our study additionally showed the solar-to-hydrogen efficiency of 27.93% and a carrier utilization efficiency of 42.83%, indicating the AlSb/ZnO heterostructure as an excellent water splitting photocatalyst with remarkable potential for fuel cells and energy storage applications.

Selective CO2 hydrogenation to methanol over a novel ternary In-Co-Zr catalyst

To address the challenges of global warming and energy shortages, the technology to convert CO2 into methanol is of great significance Indium-cobalt catalysts have attracted widespread attention due to their significant activity and excellent stability. Herein, In-Co and In-Co-Zr catalyst rich in In2O3 were prepared through a citric acid-assisted co-precipitation method. The results show that the In-Co-Zr catalyst can significantly enhance the activity for hydrogenating CO2 to methanol, achieving a CO2 conversion rate of 17.4 % and a methanol selectivity of 77.7 % under the conditions (5.0 MPa, 310 °C, GHSV = 10.28 l·gcat-1·h-1, H2/CO2 ratio of 4). At a GHSV of 48 l·gcat-1·h-1, the space–time yield of methanol was 0.79 gMeOH·gcat-1·h-1, and the catalyst exhibited stable catalytic activity over a continuous reaction period of 120 h. It was revealed that the incorporation of ZrO2 could significantly improve methanol selectivity of In-Co catalyst. Moreover, an increased oxygen vacancy and strong interaction of the In-Co-Zr catalysts are conducive to improving the CO2 adsorption strength and capacity. It is expected that this novel ternary In-Co-Zr catalyst could inspire new opportunities for designing and developing multi-component hybrid catalysts for highly active, stable and selective CO2 hydrogenation to methanol

High-homogeneous recyclable self-cured epoxy resins based on imine

The production of high-performance epoxy resins currently depends on combining rigid epoxy oligomers and non-flexible hardeners. However, the high melting points and incompatibilities of raw materials, along with the inhomogeneous crosslinked networks of thermoset resins, challenge the development of high-performance epoxy resins simultaneously enhancing strength and toughness with excellent processing properties. To address this issue, we propose a self-curing strategy to obtain a novel thermosetting epoxy resin by simply melting the epoxy oligomers containing the Schiff base structure. The mechanism of self-cured was also revealed by density functional theory. Remarkably, this method eliminates the need for curing agents, catalysts, or active hydrogen structures. The resulting self-cured epoxy resin (VEP-SC) simplifies processing steps. In particular, VEP-SC forms a more homogeneous cross-linked network and exhibits superior mechanical properties due to the unique preparation method. Compared to traditional thermosetting epoxy cured with a curing agent, the tensile strength, elongation at break, and flexural strength of VEP-SC were 133.4 %, 168.4 %, and 276.2 % higher than those of VEP-MeHHPA, respectively. Furthermore, the Schiff base structure imparts the vitrimeric behavior of self-cured epoxy resin, achieving recyclability. This approach provides innovative solutions for developing versatile and high-performance epoxy resins.

Reusable metal-free mesoporous carbon-catalyzed reductive N-formylation of nitroarenes and quinolines

The high-value transformation of nitrogen-containing compounds through a facile, cost-effective, and eco-friendly one-pot strategy holds significant importance. However, this process typically involves the use of metal catalysts and is limited by low activity as well as the requirement of high temperature and pressure. Herein, we describe a general and efficient metal-free N-doped mesoporous carbon material using well-defined ligand 1,10-phenanthroline as the precursor and silica colloid as the hard template. Formic acid is both a reducing agent and a formylation reagent, and structurally distinct mono- or multi-substituted nitroarenes and quinolines can be selectively N-formylation in a one-pot method. The catalyst can be easily recovered without observable loss of efficiency for ten consecutive uses. The control experiments and density functional theory (DFT) calculations indicate that formic acid mainly obtains active hydrogen in the form of O–H bond cleavage, which benefits from the strong adsorption and enhanced activity generated by the interaction between graphitic nitrogen species in the catalyst and formic acid. The excellent catalytic performance of the meso-phen-X catalyst is attributed to the synergistic effect of graphitic N and large specific surface area, providing a promising method for the development of non-metallic catalyst-modified carbon materials.

Bucket effect of Cobalt Nanoparticles and Single Atoms in Nitroarenes Transfer Hydrogenation

Synergetic metal nanoparticles (NPs) and single atoms hold significant potential in reactions that require activating multiple substrate molecules. However, due to the differences in adsorption, activation and kinetics among distinct substrates during the multistep reaction process, the synergy and matching relationship between metal NPs and single atoms remain unclear. In this work, we synthesized a series of Co1-NP/CNT@CN-X dual-site catalysts with tunable molar ratios (X%) of Co single atoms to total Co species through a coordination site regulation (CSR) strategy and investigated the bucket effect of the dual active sites in the transfer hydrogenation of nitro compounds. Density functional theory calculations reveal that active hydrogen generation from ammonia borane hydrolysis primarily occurs at the surface of Co NPs, while nitroarenes hydrogenation predominantly takes place at Co single atoms, which is consistent with experimental findings. The optimized Co1-NP/CNT@CN-7.6 maintains high selectivity for nitro hydrogenation (> 99.9%) and exhibits conversion (99.9%) nearly 3.7 times that of the original Co1-NP/CNT@CN-1.6 catalyst (27%), achieved by overcoming the bucket effect between Co NPs and single atoms. This work not only elucidates the synergistic mechanisms of dual sites in transfer hydrogenation, but also establishes that optimizing matching effect is an effective approach to significantly enhance their catalytic performance.

Reductive Depolymerization of Lignin to Aromatic Compounds over Promoted Nickel Catalysts in Sub‐ and Supercritical Methanol

The use of γ‐Al2O3‐supported Ni catalysts promoted with either Cu or Fe was investigated for the reductive catalytic fractionation (RCF) of hybrid poplar in methanol at 200 and 250 °C. The effectiveness of lignin depolymerization was quantified in terms of the lignin oil production, the quantity and distribution of identifiable monomers present in the lignin oil, and the yield of residual solids. All of the Ni‐based catalysts tested provided improved yields of lignin oil and monomers, along with reduced char formation, relative to blank (sans catalyst) runs. The highest monomer yield of 51% was obtained at 250 °C over a 20 wt.% Ni‐5 wt.% Cu/Al2O3 catalyst, the improved performance obtained through Cu promotion being attributed to the ability of Cu to facilitate NiO reduction, resulting in an increased amount of Ni0 on the catalyst surface and, consequently, improved hydrogenation activity. The main monomers formed were propanol‐, propyl‐ and propenyl‐substituted guaiacol and syringol, the S/G ratio of the products corresponding closely to that in the native lignin.

Core-shell Ni/SiO2@ZrO2 catalyst for highly selective CO2 conversion accompanied by enhancing reaction stability

CO2 RWGS reaction was considered to be a promising process for carbon dioxide conversion, however it retained a big challenge owing to methanation and metal sintering. Therefore, it was desperately needed to devise highly selective and stable catalyst. Herein, core-shell Ni/SiO2@ZrO2 catalyst was successfully prepared via a combination of the wet impregnation and in-situ hydrothermal synthesis method, with ZrO2 as the coating shell. The optimized Ni/SiO2@4ZrO2 catalyst possessed enhanced metal-support interaction and rich oxygen vacancies as well as abundant medium-strength CO2 adsorption sites. As a result, under the GHSV of 120000 mL/g·h and 150000 mL/g·h, Ni/SiO2@4ZrO2 displayed a considerable hydrogenation activity and significantly higher selectivity to CO, compared with the Ni/SiO2 catalyst as a reference. During stability tests, Ni/SiO2@4ZrO2 also showed a superior catalytic stability with a steady 100 % CO selectivity, carried out at 600 °C for 72 h. This work provided a novel strategy of designing a core-shell catalyst for CO2 RWGS reaction, and was expected to be put into use in other multiphase reaction process.

Precisely Tailoring the Second Coordination Sphere of a Cobalt Single-Atom Catalyst for Selective Hydrogenation of Halogenated Nitroarenes.

The development of highly efficient and cost-effective nonprecious metal catalysts for the selective hydrogenation of halogenated nitroarenes is very appealing yet challenging. Here, we demonstrate that the hydrogenation activity and selectivity of Co single-atom catalyst (SAC) can be tuned by tailoring the structure of second coordination sphere via P doping. As revealed by synchrotron radiation-based X-ray absorption spectroscopy characterizations, such a P doping on N-coordinated Co SAC results in the unsymmetric Co-N4P1 coordination structure. With a combination of experimental characterizations and theoretical simulations, we find that tailoring the second coordination sphere can greatly improve H2 dissociation and product desorption. As a result, the Co-N4P1 SAC exhibits superior activity, selectivity and stability for the hydrogenation of halogenated nitroarenes to corresponding amines (20 examples, >99% yields) at 80 oC under 0.5 MPa H2 pressure, significantly outperforming most heterogeneous catalysts reported in the literature. We expect that this work opens a new avenue for the design of highly efficient nonprecious metal SACs for important hydrogenation reactions.

Precisely Tailoring the Second Coordination Sphere of a Cobalt Single‐Atom Catalyst for Selective Hydrogenation of Halogenated Nitroarenes

The development of highly efficient and cost‐effective nonprecious metal catalysts for the selective hydrogenation of halogenated nitroarenes is very appealing yet challenging. Here, we demonstrate that the hydrogenation activity and selectivity of Co single‐atom catalyst (SAC) can be tuned by tailoring the structure of second coordination sphere via P doping. As revealed by synchrotron radiation‐based X‐ray absorption spectroscopy characterizations, such a P doping on N‐coordinated Co SAC results in the unsymmetric Co‐N4P1 coordination structure. With a combination of experimental characterizations and theoretical simulations, we find that tailoring the second coordination sphere can greatly improve H2 dissociation and product desorption. As a result, the Co‐N4P1 SAC exhibits superior activity, selectivity and stability for the hydrogenation of halogenated nitroarenes to corresponding amines (20 examples, >99% yields) at 80 oC under 0.5 MPa H2 pressure, significantly outperforming most heterogeneous catalysts reported in the literature. We expect that this work opens a new avenue for the design of highly efficient nonprecious metal SACs for important hydrogenation reactions.

Controlling Hydrogen Evolution and CO2 Reduction at Transition Metal Hydrides.

ConspectusFuel-forming reactions such as the hydrogen evolution reaction (HER) and CO2 reduction (CO2R) are vital to transitioning to a carbon-neutral economy. The equivalent oxidation reactions are also important for efficient utilization in fuel cells. Metal hydride intermediates are common in these catalytic and electrocatalytic processes. Guiding metal hydride reactivity is important for achieving selective, kinetically fast, and low overpotential redox reactions. Our work has focused on understanding kinetic and thermodynamic aspects for controlling these reactive hydride species in an effort to design more selective electrocatalysts that operate at low overpotentials. Key to our research approach is understanding the free energy changes and rate of discrete steps of catalysis through the synthesis of proposed intermediates to independently investigate catalytic steps. Hydricity, the free energy of hydride dissociation, and how these values change with metal and ligand environment have informed catalyst design in the past few decades. We describe here how we have advanced upon these earlier studies.In our early studies we sought to understand solvent-dependent changes in hydricity for transition metal hydrides and how they impact the free energy for reduction of CO2 to formate (HCO2-). Additionally, we described how hydricity values can be applied to optimize HER and CO2R catalysis. This framework provides general guidelines for achieving selective CO2 reduction to formate without concomitant generation of H2. Kinetic information on steps in the proposed catalytic cycle of HER and CO2R catalysts were evaluated to identify potential rate-determining steps. As a second approach to achieve selective reduction for CO2, we explored two catalyst design strategies to kinetically inhibit HER using electrostatic (charged) and steric interactions. Hydricity values and other considerations for minimizing the free energy of proposed catalytic steps were also used to design an electrocatalyst for the interconversion between CO2 and HCO2- at low overpotentials. Further, we discuss our efforts to translate the CO2 hydrogenation activity of homogeneous catalysts to electrocatalysis.All of these catalytic systems operate with classical metal hydrides, where the electrons and proton are colocated on the metal center. However, classical metal hydrides all require very reducing potentials to generate sufficiently strong hydride donors for CO2 reduction. An analysis of metal hydride hydricity and reduction potentials shows that the strong correlation between reduction potential and hydricity is a general trend because the former is also highly correlated to pKa. However, formate dehydrogenase (FDH) generates a competent hydride donor at more mild potentials through bidirectional hydride transfer, where the proton and electrons of the hydride are not colocated. This bioinspired approach points to a promising new strategy for generating strong hydride donors at milder potentials and will surely open new avenues for using hydricity as a guide for addressing new and existing problems in catalysis.

Atomic Scale Cooperativity of Alloy Nanostructures for Efficient Nitrate Electroreduction to Ammonia in Neutral Media

AbstractElectrochemical nitrate reduction reaction (NO3RR) offers a route to balanced nitrogen cycle and sustainable ammonia production. However, unsatisfied performance in neutral media arising from competitive hydrogen evolution reaction and inefficient hydrogenation impede the further applications of NO3RR. Herein, the rational design of RuNi alloy nanostructures is reported. Benefited from the synergism effect between Ru and Ni, Ru20Ni80 alloy exhibits a high NH3 Faradaic efficiency of 98.02% at −0.35 V (vs reversible hydrogen electrode (RHE)) and a large NH3 yield rate of 27.88 mg mgcat−1 h−1 at −0.65 V (vs RHE). Importantly, the atomic scale cooperation between Ru and Ni active sites endows RuNi alloy a close‐to‐unity NH3 selectivity via HNO* pathway. Theoretical calculations have revealed that the interactions between Ru and Ni optimize the electronic structures of Ru20Ni80 alloy, where Ru sites with enhanced electroactivity improve the generation of active hydrogens and more electron‐rich Ni sites facilitate the reduction of nitrate. Accordingly, the adsorption strengths of key intermediates become stronger and the energy barriers of NO3RR are reduced to guarantee efficient NO3RR. Furthermore, a flow‐type reactor coupled with coprecipitation is established to achieve continuous NH3 generation and recovery as struvite.

Structural and Electronic Modulations of Se-Vacancy-Rich MoSe2 Triggered by Cr Doping toward Robust Nitrogen Reduction Reaction.

The electrocatalytic nitrogen reduction reaction (NRR) is proposed as an alternative to the Haber-Bosch process, but the development of efficient NRR electrocatalysts remains a challenging task. MoSe2 has superior conductivity compared to MoS2, making it promising in the NRR field. Unfortunately, the scarcity of active sites and competitive hydrogen evolution reaction (HER) hinder its broader applications. Here, Se-vacancy-rich MoSe2 is designed through Cr doping, allowing for targeted regulations of architectural and electronic structure by leveraging the dual effects of doping and VSe. Further mechanistic studies innovatively find that the Cr-induced multi-vacancy (18.75% concentration) exerts inverse contributions to NRR on 2H- and 1T-MoSe2, reflecting boosted and depressed effects, respectively. Consequently, suitable doping effectively facilitates NRR and eases the competition from HER, realizing excellent NH3 yield (51.53±2.45µgh-1mg-1 cat) and Faradaic efficiency (63.37%) in MSC-1. This work paves the opportunity for MoSe2-based electrocatalysts toward boosted NRR.

Boosting piezocatalytic activity for hydrogen bonding self-assembled Ti3C2/BaTiO3 heterojunction via accumulated piezoelectric effect

Constructing heterojunctions has been proved to effectively improve the carrier transfer capability for enhanced catalytic activity. Herein, Ti3C2/BaTiO3 heterojunctions were fabricated through self-assembly driven by hydrogen bonding between piezoelectric barium titanate (BaTiO3) stabilized by oleic acid molecules and titanium carbide (Ti3C2) with surficial functional groups under continuous ultrasonic vibration. Owing to the formation of heterojunction, the separation of free charges can be promoted by the conductive Ti3C2. Additionally, the recombination of electrons and holes pairs in BaTiO3 can be hindered by built-in piezoelectric field. Hence, the piezocatalytic activity of Ti3C2/BaTiO3 was significantly enhanced by the accumulated piezoelectric effect, maintaining stability during the piezocatalytic degradation of bisphenol A and achieving rate constants that were 22.2 and 3.2 times higher than those of Ti3C2 and BaTiO3, respectively. This work thus presents a novel strategy for designing high-activity heterojunction piezocatalysts through hydrogen bonding self-assembly.