Hydrogenation Activity Research Articles

Synergize Strong and Reactive Metal-Support Interactions to Construct Sub-2 nm Metal Phosphide Cluster for Enhanced Selective Hydrogenation Activities.

Strong metal-support interactions (SMSI) are crucial for stabilizing sub-2 nm metal sites, e.g. single atom (M1) or cluster (Mn). However, further optimizing sub-2 nm sites to break the activity-stability trade-off due to excessive interactions remains significant challenges. Accordingly, for the first time, we propose synergizing SMSI with reactive metal-support interactions (RMSI). Comprehensive characterization confirms that the SMSI stabilizes the metal and regulates the aggregation of Ni1 into Nin site within sub-2 nm. Meanwhile, RMSI modulates Nin through sufficiently activating P in the support and eventually generates sub-2 nm metal phosphide Ni2P cluster (Ni2Pn). The synergetic metal-support interactions triggered the adaptive coordination and electronic structure optimization of Ni2Pn, leading to the desired substrate adsorption-desorption kinetics. Consequently, the activity of Ni2Pn site greatly enhanced towards the selective hydrogenations of p-chloronitrobenzene and alkynyl alcohol. The formation rates of target products are up to 20.2 and 3.0 times greater than that of Ni1 and Nin site, respectively. This work may open a new direction for metal-support interactions and promote innovation and application of active sites below 2 nm.

Modulating Hydrogen Adsorption by Unconventional p–d Orbital Hybridization over Porous High‐Entropy Alloy Metallene for Efficient Electrosynthesis of Nylon‐6 Precursor

AbstractRenewable electricity driven electrosynthesis of cyclohexanone oxime (C6H11NO) from cyclohexanone (C6H10O) and nitrogen oxide (NOx) is a promising alternative to traditional environment‐unfriendly industrial technologies for green synthesis of C6H11NO. Precisely controlling the reaction pathway of the C6H10O/NOx‐involved electrochemical reductive coupling reaction is crucial for selectively producing C6H11NO, which is yet still challenging. Herein, we report a porous high‐entropy alloy PdCuAgBiIn metallene (HEA‐PdCuAgBiInene) to boost the electrosynthesis of C6H11NO from C6H10O and nitrite, achieving a high Faradaic efficiency (47.6 %) and almost 100 % yield under ambient conditions. In situ Fourier transform infrared spectroscopy and theoretical calculations demonstrate that unconventional orbital hybridization between d‐block metals and p‐block metals could regulate the local electronic structure of active sites and induce electron localization of electron‐rich Pd sites, which tunes the active hydrogen supply, facilitates the generation and enrichment of key intermediates NH2OH* and C6H10O*, and efficiently promotes their C−N coupling to selectively produce C6H11NO.

Effect of active site size in dispersed MoS2 nanocatalysts on slurry-phase hydrocracking of residue

This work investigates the influence of active site size in dispersed MoS2 on the slurry-phase hydrocracking of Merey residue (MRR). MoS2 nanocatalysts with varying morphologies were synthesized using the ligand sulfurization method, employing molybdenum oleate as the Mo precursor. The results demonstrate that mono-layered or double-layered MoS2 plates with slab sizes of 3 ∼ 10 nm can be synthesized at a sulfurization temperature of 400 °C and a sulfurization time of 0.5 h. Prolonged sulfurization time results in the growth and agglomeration of MoS2 plates, leading to multi-layered slabs with increased length and larger particle size, as well as a wider distribution range. The MoS2-0.5 (prepared with a sulfurization time of 0.5 h) exhibits superior hydrocracking activity, effectively converting resin and asphaltene into light fractions and significantly suppressing coke formation. Specifically, the conversion rates of resin and asphaltene are 51.3 wt% and 92.1 wt%, respectively, with the minimal coke yield of 0.6 wt% under conditions of 430 °C, 1 h, 7 MPa initial H2, and a catalyst dosage of 500 μg/g. The catalytic activity of the MoS2 nanocatalysts exhibits a strong correlation with their size and morphology obtained at different sulfurization times. Density functional theory (DFT) calculations reveal that MoS2 with smaller slab sizes are more beneficial for the adsorption and dissociation of H2, due to higher adsorption energy (Eads) and lower activation barrier (Ea). This facilitates the generation of sufficient active hydrogen to encourage the hydrocracking of residue and suppress coke formation.

Synthesis of Palladium Nanomaterials Using Plant Leaf Extract and their Enhanced Photocatalytic Activities against Organic Dyes

Aims and Objectives: This study aimed to carry out the green synthesis of palladium nanoparticles (Pd NPs) using the aqueous leaves extract of Eclipta alba. The appearance of a characteristic surface plasmon resonance peak at 410 nm confirmed the synthesis of Pd NPs. Method: The average particle sizes of 13 nm were observed by using the leaf concentrations of 10 mL with a certain amount of PdCl2 (0.001 M) at 25 ̊ C. The Pd NPs, as synthesized under the optimized conditions (10 mL extract + 60 ̊ C + 0.001 M PdCl2), were spherical in shape, small in size, and uniformly distributed, as depicted by HR-TEM images. Results: FTIR, XRD, DLS, and zeta potential further confirmed the formation of Pd NPs. The Pd NPs synthesized at optimized conditions exhibited strong catalytic activity in dye Eosin yellow, Rose Bengal, Tartrazine, and Ponceau S degradation by discoloration of dyes in 3 hrs. The removal of all dyes by the Pd NPs was optimized by varying specific operating parameters, such as initial dye concentration, solution pH, irradiation time, and temperature. Conclusion: This high activity of Pd NPs may be due to their small size, high dispersion, and surface- capping phytochemicals. result: Bio-fabrication of metallic Pd NPs using different plant extracts compared to other reducing agents is more scalable, rapid, and cost-effective for generating bulk nanoparticles. The phytochemical principles, such as phytoconstituents, reduce the PdCl2 to Pd NPs and are implicated in the capping and stability of the nanoparticles. Hence, the leaves of Eclipta alba have different polyols and are well known. Apart from this, hydroxyl groups in phenolic compounds may participate in the bio-reduction of PdCl2. Such compounds can chelate metal ions to form their quinones form, which is an intermediate palladium complex. Then, stabilization of the intermediate form and reduction of Pd2+ to Pd0 occurred due to free electrons or nascent hydrogen produced during the bio-reduction reaction. Finally, Pd-NPs were prepared due to the collision of neighboring Pd0 atoms. These significant conjugations exist in the keto-enol system within the quinone form of the compound.

Synthesis and consequence of three-dimensionally ordered macroporous Beta zeolite supported NiW catalyst for efficient hydrocracking of 1-methylnaphthalene to BTX

The three-dimensionally ordered macroporous Beta (3DOM-Beta) zeolite was prepared and used as support of NiW sulfide catalyst for hydrocracking. The as-prepared NiW/3DOM-Beta catalyst possessed a high specific surface area and external specific surface area up to 499 m2/g and 241 m2/g, respectively, and a small average layer length (3.62 nm), a high highest average stacking number (4.64) and dispersion (fW=0.24) of metal sulfide phase, which are characteristic of high hydrogenation activity. Its high mesopore volume (0.25 cm3/g) and the highly ordered interconnected macro-meso-microporosity hierarchical structure significantly facilitated diffusive mass transfer. Compared to the NiW sulfide supported on conventional Beta (C-Beta), alkali-treated Beta (A-Beta) and nanosized Beta (Nano-Beta) zeolites, NiW/3DOM-Beta catalyst showed the highest BTX selectivity and yield of 40.7 % and 40.2 % (33.2 % and 32.6 % on NiW/C-Beta, 34.8 % and 33.9 % on NiW/A-Beta, 37.2 % and 36.6 % on NiW/Nano-Beta), and the highest hydrocracking activity (TOF=2.11 × 10-2∙s−1) as well as the smallest coking content (6.7 wt%). This work not only reveals the promotion effects of the ordered mesopore structure of supports on metal dispersion, accessibility of acid sites, diffusion of reactants and products for designing hydrocracking catalyst, but also shows the potential practical application of 3DOM zeolites with interconnected macro-meso-microporosity for the efficient catalytic conversion of macro-hydrocarbons via hydroupgrading.

Expanding the scope of resonance Raman spectroscopy in hydrogenase research: New observable states and reporter vibrations

Oxygen-tolerant [NiFe] hydrogenases are valuable blueprints for the activation and evolution of molecular hydrogen under application-relevant conditions. Vibrational spectroscopic techniques play a key role in the investigation of these metalloenzymes. For instance, resonance Raman spectroscopy has been introduced as a site-selective approach for probing metal-ligand coordinates of the [NiFe] active site and FeS clusters. Despite its success, this approach is still challenged by a limited number of detectable active-site states – due to missing resonance enhancement or intrinsic light sensitivity – and difficulties in their assignment. Utilizing two oxygen-tolerant [NiFe] hydrogenases as model systems, we illustrate how these challenges can be met by extending excitation and detection wavelength regimes in resonance Raman spectroscopic studies. Specifically, we observe that this technique does not only probe low-frequency metal-ligand vibrations but also high-frequency intra-ligand modes of the diatomic CO/CN− ligands at the active site of [NiFe] hydrogenases. These reporter vibrations are routinely probed by infrared absorption spectroscopy, so that direct comparison of spectra from both techniques allows an unambiguous assignment of states detected by resonance Raman spectroscopy. Moreover, we find that a previously undetected state featuring a bridging hydroxo ligand between Ni and Fe can be probed using higher excitation wavelengths, as photoconversion occurring at lower wavelengths is avoided. In summary, this study expands the applicability of resonance Raman spectroscopy to hydrogenases and other complex metalloenzymes by introducing new strategies for probing and assigning redox-structural states of the active site.

Rational Design and Modification of NphB for Cannabinoids Biosynthesis.

The rapidly growing field of cannabinoid research is gaining recognition for its impact in neuropsychopharmacology and mood regulation. However, prenyltransferase (NphB) (a key enzyme in cannabinoid precursor synthesis) still needs significant improvement in order to be usable in large-scale industrial applications due to low activity and limited product range. By rational design and high-throughput screening, NphB's catalytic efficiency and product diversity have been markedly enhanced, enabling direct production of a range of cannabinoids, without the need for traditional enzymatic conversions, thus broadening the production scope of cannabinoids, including cannabigerol (CBG), cannabigerolic acid (CBGA), cannabigerovarin (CBGV), and cannabigerovarinic acid (CBGVA). Notably, the W3 mutant achieved a 10.6-fold increase in CBG yield and exhibited a 10.3- and 20.8-fold enhancement in catalytic efficiency for CBGA and CBGV production, respectively. The W4 mutant also displayed an 9.3-fold increase in CBGVA activity. Molecular dynamics simulations revealed that strategic reconfiguration of the active site's hydrogen bonding network, disulfide bond formation, and enhanced hydrophobic interactions are pivotal for the improved synthetic efficiency of these NphB mutants. Our findings advance the understanding of enzyme optimization for cannabinoid synthesis and lay a foundation for the industrial-scale production of these valuable compounds.

High-Density Atomically Dispersed Metals Activate Adjacent Nitrogen/Carbon Sites for Efficient Ammonia Electrosynthesis from Nitrate.

While electrocatalytic reduction of nitrate to ammonia presents a sustainable solution for addressing both the environmental and energy issues within the nitrogen cycle, it remains a great challenge to achieve high selectivity and activity due to undesired side reactions and sluggish reaction kinetics. Here, we fabricate a series of metal-N-C catalysts that feature hierarchically ordered porous structure and high-density atomically dispersed metals (HD M1/PNC). Specifically, the as-prepared HD Fe1/PNC catalyst achieves an ammonia production rate of 21.55 mol gcat-1 h-1 that is at least 1 order of magnitude enhancement compared with that of the reported metal-N-C catalysts, while maintaining a 92.5% Faradaic efficiency when run at 500 mA cm-2 for 300 h. In addition to abundant active sites, such high performance benefits from the fact that the high-density Fe can more significantly activate the adjacent N/C sites through charge redistribution for improved water adsorption/dissociation, providing sufficient active hydrogen to Fe sites for nitrate ammoniation, compared with the low-density counterpart. This finding deepens the understanding of high-density metal-N-C materials at the atomic scale and may further be used for designing other catalysts.

N, P Dual-Doped Carbons as Metal-Free Catalysts for Hydrogenation.

The activation of molecule hydrogen (H2) by metal-free catalysts is always a challenge in the field of catalysis. Herein, a series of N, P dual-doped carbon catalysts were constructed by the pyrolysis of chitosan and phytic acid and utilized as metal-free catalysts for the hydrogenation of nitrobenzene. The characterization indicated that the doping of phosphorus atoms not only formed the species with catalytic activity for hydrogenation reaction but also promoted the doping of N. The experimental results indicated that their catalytic performance could be improved by the regulation of pyrolysis temperature and heating rate. CP-900-1 (pyrolysis at 900 °C with a heating rate of 1 °C/min) exhibited a promising catalytic activity with >99% nitrobenzene conversion. N, P codoping was the key factor to its catalytic performance. All results indicated that the excellent catalytic activity of CP-900-1 was attributed to the synergistic interaction among pyridinic N, P-C species, and graphitic N. This work provides an effective route for the rational design and construction of highly efficient metal-free catalysts for hydrogenation.

Engineering Nickel Dopants in Atomically Thin Molybdenum Disulfide for Highly Efficient Nitrate Reduction to Ammonia

AbstractThe electrocatalytic nitrate reduction reaction (NO3−RR) presents a promising pathway for achieving both ammonia (NH3) electrosynthesis and water pollutant removal simultaneously. Among various electrocatalysts explored, 2D materials have emerged as promising candidates due to their ability to regulate electronic states and active sites through doping. However, the impact of doping effects in 2D materials on the mechanism of NO3−RR remains relatively unexplored. Here, Ni‐doped MoS2 (Ni‐MoS2) nanosheets are investigated as a model system, demonstrating enhanced NO3−RR performance compared to undoped counterparts. By controlling the doping concentration, the Ni‐MoS2 nanosheets achieve a remarkable faradic efficiency (FE) of 92.3% for NH3 at −0.3 VRHE with excellent stability. The mechanistic studies reveal that the elevation of the NO3−RR performances originates from the generation of more active hydrogen and the acceleration of the reaction from nitrite (NO2−) to NH3 facilitated by Ni doping. Combining the experimental observations and theoretical calculations it is revealed that the appropriate Ni doping level in MoS2 can enhance *NO3 adsorption strength, thereby facilitating subsequent electrocatalytic steps. Together with the demonstration of Zn−NO3− and Zn−NO2− battery devices, the work provides new insights into the design and regulation of the active sites in 2D material catalysts for efficient NO3−RR.

Fabrication of V2O3-TiO2-rGO ternary heterojunction composite to enhance the hydrogen storage performance of MgH2

The application prospects of MgH2 as a potential solid hydrogen storage material are limited by its stable thermodynamic properties and slow hydrogenation/dehydrogenation kinetics. In this study, a ternary heterogeneous composite material V2O3-TiO2-rGO (V-T-rGO) was synthesized using the ultrasonic hydrothermal method and doped into MgH2 through ball milling to improve its hydrogen storage performance. The experimental results demonstrated that the MgH2 + V-T-rGO samples exhibit superior hydrogen storage properties compared with single-doped V2O3, TiO2, rGO or V-T materials. Specifically, it can uptake hydrogen at room temperature, and adsorbs 5.00 wt% H2 in just 4 min at 150 °C, and releases 5.87 wt% H2 within 6 min at 325 °C, demonstrating a faster reaction rate and successful hydrogen absorption. Additionally, the hydrogenation/dehydrogenation activation energies of MgH2 + V-T-rGO samples are measured at 27.1/72.3 kJ·mol−1, representing a reduction of 51.2/59.2 kJ·mol−1 compared to MgH2 alone. Mechanistic analysis revealed that the multiphase composite system produced synergistic catalytic effects, providing abundant active sites and hydrogen diffusion channels to enhance the hydrogen storage performance of MgH2. This study presents an innovative approach for constructing transition metal oxide heterostructured materials and holds significant reference value for applications in the field of hydrogen storage.

Theoretical Understandings on Mechanisms of Hydrogenation Activities Using Graphene‐Based Single‐Atom Catalysts

AbstractMetal single‐atom catalysts (SACs) have emerged as a promising class of catalysts in various fields, owing to their well‐defined active centers, tunable coordination environments, and high reaction selectivity. Among the diverse supports, graphene‐based SACs have garnered significant attention due to their exceptional properties in hydrogenation reactions. This review elucidates recent advancements in theoretical investigations of the electronic and geometric structures of metal SACs, with a focus on modulation strategies such as coordination number adjustment, heteroatom doping, defect site engineering, and frustrated Lewis pair construction. This review emphasizes atomic‐level insights into the hydrogenation reaction mechanism in thermocatalysis, including the activation of the H‐source molecules, hydrogen diffusion, and elementary reaction steps. Strategies for modulating the catalytic activity of SACs are summarized. Lastly, this review offers perspectives on the design of effective graphene‐based SACs from theoretical standpoint, paving the way for future research in this exciting field.

Pd catalysts in the mild reductive depolymerization of Soda lignin: Support and Cu addition effects

This study pioneers the exploration of the structure-performance relationship of 5 wt% Pd and PdCu catalysts on 3 supports (γ-Al2O3, SiO2, and activated carbon (AC)) in the mild reductive depolymerization (MRD) of Soda lignin. While all catalysts achieve similar final weight average molecular weight (Mw) reduction (≈ 85 %), Pd/AC and PdCu/AC show significant differentiation from solvolysis already after 2 h and 3 h, compared to 6 h and 20 h for Pd and PdCu on oxide supports. This study also highlights the importance of hydrogenation of C=C bonds in monomer side-chains for maximizing monomer yields. Particularly PdCu/SiO2 is characterized by the lowest monomer yields (7 wt%) due to its low hydrogenation activity, while catalysts like Pd(Cu)/Al2O3, Pd/SiO2, and Pd/AC, with more expressed hydrogenation, achieve a total monomer yield of up to 14 wt%. Additional findings confirm that on γ-Al2O3, the co-impregnation of Cu and Pd leads to the formation of a chemical bond between Pd2+ and Cu1+, resulting in a new mixed metal oxide Pd-Cu–O phase. On SiO2, Pd2+ and Cu1+ do not form a chemical bond, however, the presence of Cu1+ in close proximity to Pd2+ significantly alters the selectivity of the PdCu/SiO2 catalyst due to synergetic effects. PdCu/AC maintains similar selectivity to Pd/AC, except for reduced hydrogenation over time, due to the lack of interaction between Pd and Cu on the AC surface. This research also delves into the MRD mechanism of Soda lignin over Pd and PdCu catalysts, focusing on the β-O-4 linkage cleavage and the subtle differences in reaction pathways depending on the catalyst. These findings bridge gaps in understanding the MRD of actual lignin feedstocks, offering valuable insights for catalyst development and process optimization.

Triple Regulations via Fe Redox Boosting Nitrate Reduction to Ammonia at Industrial Current Densities

Electrochemical nitrate reduction reaction (NO3‐RR) has promising prospects for green synthesis of ammonia and environmental remediation. However, the performance of catalysts at high current density usually suffers from the high energy barrier for the nitrate (NO3‐) to nitrite (NO2‐) and the competitive hydrogen evolution. Herein, we proposed a two‐step relay mechanism through spontaneous redox reaction followed electrochemical reaction by introducing low‐valence Fe species into Ni2P nanosheets to significantly enhance the NO3‐RR performance at industrial current density. The existence of low‐valence Fe species bypasses the NO3‐ to NO2‐ step through the spontaneous redox with NO3‐ to produce NO2‐ and Fe2O3, regulates the electronic structure of Ni2P to reduce the barrier of NO2‐ to NH3, thirdly prohibits the hydrogen evolution by consuming the excess active hydrogen through reduction of Fe2O3 to recover low‐valence Fe species. The triple regulations via Fe redox during the two‐step relay reactions guarantee the Fe‐Ni2P@NF high ammonia yield of 120.1 mg h‐1 cm‐2 with Faraday efficiency of more than 90% over a wide potential window and a long‐term stability of more than 130 h at ~1000 mA cm‐2. This work provides a new strategy to realize the design and synthesis of nitrate reduction electrocatalysts at high current densities.

Triple Regulations via Fe Redox Boosting Nitrate Reduction to Ammonia at Industrial Current Densities.

Electrochemical nitrate reduction reaction (NO3-RR) has promising prospects for green synthesis of ammonia and environmental remediation. However, the performance of catalysts at high current density usually suffers from the high energy barrier for the nitrate (NO3-) to nitrite (NO2-) and the competitive hydrogen evolution. Herein, we proposed a two-step relay mechanism through spontaneous redox reaction followed electrochemical reaction by introducing low-valence Fe species into Ni2P nanosheets to significantly enhance the NO3-RR performance at industrial current density. The existence of low-valence Fe species bypasses the NO3- to NO2- step through the spontaneous redox with NO3- to produce NO2- and Fe2O3, regulates the electronic structure of Ni2P to reduce the barrier of NO2- to NH3, thirdly prohibits the hydrogen evolution by consuming the excess active hydrogen through reduction of Fe2O3 to recover low-valence Fe species. The triple regulations via Fe redox during the two-step relay reactions guarantee the Fe-Ni2P@NF high ammonia yield of 120.1 mg h-1 cm-2 with Faraday efficiency of more than 90% over a wide potential window and a long-term stability of more than 130 h at ~1000 mA cm-2. This work provides a new strategy to realize the design and synthesis of nitrate reduction electrocatalysts at high current densities.

Design of self-healing and anticorrosion epoxy coating with active multiple hydrogen bonds based on grafted polyetheramine

The healing of epoxy coatings in damaged areas significantly influences their service life and protection quality. Intrinsic self-healing coatings, which enable multiple healing cycles without the need for additional functional carriers, have emerged as a promising coating technology. Nevertheless, the cross-linked structure of thermoset epoxy coating system restricts the large-scale migration of molecular chains, posing a significant challenge to achieve intrinsic healing of resin without compromising its mechanical properties. In this study, we report a design scheme for epoxy coating with intrinsic self-healing properties based on active multiple hydrogen bonds. Grafting aminobenzothiazole at the end of polyetheramine D230 chain, the grafted polyetheramine (GD230) was synthesized and served as the auxiliary curing agent, whose accurate molecular structure has been confirmed by different characterizations. The self-healing coating with reversible dynamics network based on hydrogen bonds was prepared by crosslinking through epoxy resin and mixed curing agent of polyetheramine D230 and GD230. Various measurements have been adopted to evaluate the self healing and anticorrosion performance. Results showed that the functional coating with a ratio of 8:2 for D230 to GD230 has satisfied both performances on the steel substrate. After immersion in 3 wt% NaCl solution for 120 days, the impedance value of functional coating still remains about 1010 Ω cm2. After the coating was scratched and immersion for 96 h, the impedance value of functional coating increased by about two orders of magnitude compared to that in blank coating. Mechanical testing and theoretical calculations were used to support dynamic crosslinking model to reveal the self-healing mechanism.

Incorporation of Pd Single‐Atom Sites in Perovskite with an Excellent Selectivity toward Photocatalytic Semihydrogenation of Alkynes

AbstractSemihydrogenation is a crucial industrial process. Noble metals such as Pd have been extensively studied in semihydrogenation reactions, owing to their unique catalytic activity toward hydrogen activation. However, the overhydrogenation of alkenes to alkanes often happens due to the rather strong adsorption of alkenes on Pd active phases. Herein, we demonstrate that the incorporation of Pd active phases as single‐atom sites in perovskite lattices such as SrTiO3 can greatly alternate the electronic structure and coordination environment of Pd active phases to facilitate the desorption of alkenes rather than further hydrogenation. Furthermore, the incorporated Pd sites can be well stabilized without sintering by a strong host–guest interaction with SrTiO3 during the activation of H species in hydrogenation reactions. As a result, the Pd incorporated SrTiO3 (Pd‐SrTiO3) exhibits an excellent time‐independent selectivity (>99.9 %) and robust durability for the photocatalytic semihydrogenation of phenylacetylene to styrene. This strategy based on incorporation of active phases in perovskite lattices will have broad implications in the development of high‐performance photocatalysts for selective hydrogenation reactions.

Polymer-Supported Pd Nanoparticles for Solvent-Free Hydrogenation.

Breaking the trade-off between activity and stability of supported metal catalysts has been a long-standing challenge in catalysis, especially for metal nanoparticles (NPs) with high hydrogenation activity but poor stability. Herein, we report a porous poly(divinylbenzene) polymer-supported Pd NP catalyst (Pd/PDVB) with both high activity and excellent stability for the solvent-free hydrogenation of nitrobenzene, even at ambient temperature (25 °C) and H2 pressure (0.1 MPa). Pd/PDVB gave a turnover frequency as high as 22,632 h-1 at 70 °C and 0.4 MPa, exceeding 5556 h-1 of the classical Pd/C catalyst under equivalent conditions. Mechanistic studies reveal that the polymer support benefits the desorption of the aniline product from the Pd surface, which is crucial for rapid hydrogenation under solvent-free conditions. In addition, the polymer support in Pd/PDVB efficiently hindered Pd leaching, resulting in good stability.

Promoting Water Dissociation and Weakening Active Hydrogen Adsorption to Boost the Hydrogen Transfer Reaction over a Cu-Ag Superlattice Electrocatalyst.

The prerequisite for electrocatalytic hydrogenation reactions (EHRs) is H2O splitting to form surface hydrogen species (*H), which occupy catalytic sites and lead to mismatched coverage of *H and reactants, resulting in unsatisfactory activity and selectivity. Thus, modulating the splitting pathway of H2O is significant for optimizing the EHR process. Herein, a Cu-Ag alloy with a superlattice structure of staggered-ordered Cu and Ag is theoretically predicted and experimentally proven to undergo a pathway for H2O splitting called the hydrogen transfer reaction (HTR) in the water layer, which involves the formation of *H, the capture of *H by a water cluster to form H*(H2O)x and subsequent hydrogenation reactions by H*(H2O)x. Taking acetylene hydrogenation as a model case, the as-proposed HTR pathway could lead to a relaxation hydrogenation process to modulate the matching degree of C2H2 and *H, thus enabling a 91.2% C2H4 Faradaic efficiency at a partial current density of 0.38 A cm- 2, greatly outperforming its counterpart without a superlattice structure.

Engineering CoO/B heterojunction electrocatalysts for boosting electrocatalytic nitrate reduction to ammonia

Electrocatalytic nitrate reduction to ammonia represents a one-stone-two-birds approach for mitigating nitrate pollution and large-scale ammonia production. However, due to its multiple-electron process, it faces challenges regarding unsatisfactory Faraday efficiency (FE) and ammonia yield rate. Herein, a novel heterojunction electrocatalyst with sub-nanometric cobaltous oxide (CoO) decorated boron (B) nanosheets for electrocatalytic nitrate reduction (NO3RR) is first presented as an efficient electrocatalyst. The CoO/B heterojunction electrocatalyst exhibits a noteworthy NO3RR performance with an ammonia FE and yield rate of 95.41 % and 29.42 mg h-1 mgcat-1, respectively, in alkaline media at −0.4 V vs. reversible hydrogen electrode (RHE), surpassing CoO and B catalysts. Results demonstrated that the synergistic effect of CoO and B enhances the adsorption and activation of NO3−, lowers the formation energy of *NOH and provides sufficient active hydrogen to facilitate hydrogenation, thereby enhancing NO3RR performance. This work presents a novel approach for constructing cost-effective and high-performance NO3RR heterojunction electrocatalysts.