Hydrogenation Activity Research Articles

Hydrogen activation and surface exchange over La0.8Sr0.2Ga0.8Mg0.2O3–z

Hydrogen mass-transfer between molecular hydrogen and La0.8Sr0.2Ga0.8Mg0.2O3–z (LSGM) has been studied by means of hydrogen isotope exchange with gas phase equilibration. The measurements were carried out within a temperature range of 300–700 °C, with molecular hydrogen pressures of 100, 150 and 200 Pa. It was found that LSGM is capable of consuming hydrogen from the gas phase. The relative number of hydrogen atoms in the LSGM structure varied between 1 and 4 mol.%. The kinetics of hydrogen isotope redistribution revealed that the mass-transfer mechanism between molecular hydrogen in the gas phase and LSGM includes at least three steps. The first two relate to dissociative and associative/molecular adsorption of molecular hydrogen, while the third, identified as the rate-determining step in the exchange process, relates to hydrogen incorporation into LSGM structure. The kinetic and thermodynamic isotope effects of the exchange were estimated.

Role of electrons and H* in electrocatalytic nitrate reduction to ammonium for CuNi alloy

Electrocatalytic reduction of nitrate (NO3-) to ammonium (NH4+) is an environment friendly approach for treating nitrogen-containing wastewater. Consequently, electrocatalysts capable of effectively and selectively reducing NO3- to NH4+ receives growing attention. However, Cu-based catalysts demonstrate limited efficiency and the drawback of generating toxic NO2- though it is prevalent in the field of electrocatalytic reduction of NO3- (NO3RR). In this work, a CuNi alloy was synthesized on a Co foil through electrodeposition (marked as CuNi@Co) and its electrocatalytic performance for NO3RR was evaluated. XRD, EDS mapping and XPS characterization indicate CuNi exists with alloy state. Electrocatalytic experiments demonstrate that CuNi@Co exhibits an exceptional FENH3 of 99.12% at -0.64 V (vs. RHE). Importantly, no detrimental NO2- generated during NO3RR process because the reduction rate from NO2- to NH4+ is faster than that from NO3- to NO2-. Mechanistic analysis suggests that Cu serves as a ‘reservoir’ to provide electrons to facilitate the reduction of NO3- to NO2- during NO3RR process and the synergistic effect of Ni and Cu promotes more active hydrogen (H*) to participate the reduction process of NO2- to NH4+ not H2 generation, ultimately improving FENH3. This work elucidates the role of electrons and H* in electrocatalytic nitrate reduction to ammonium for CuNi alloy, providing new insights into the reduction process of NO3RR for Cu-based materials.

Distillery-Waste-Derived C-SiO2 Catalyst Support Reinforces Phenol Adsorption and Selective Hydrogenation.

Selective hydrogenation of lignin-derived phenolic compounds is an essential process for developing the sustainable chemical industry and reducing dependence on nonrenewable resources. Herein, a composite C-SiO2 material (DGC) was prepared via the stepwise pyrolysis and steam activation of the distiller's grains, a fermentation solid waste from the Chinese liquor industry. After Ru loading, Ru/DGC was used for the catalytic hydrogenation of phenol to cyclohexanol. Steam activation remarkably increased the hydrophilicity and specific surface area of DGC, introducing oxygen-containing functional groups on the surface of DGC, thereby promoting the adsorption of Ru3+ and phenol. Additionally, the large specific surface area facilitated the dispersion of the active metal. Furthermore, the steam activation of DGC promoted the graphitization of the carbon matrix and formed Si-H/Si-OH bonds on the SiO2 surface. The benzene ring of phenol interacted with the carbon matrix via π-π stacking, and the hydroxyl group of phenol interacted with SiO2 via hydrogen bonding. The synergistic interactions of phenol at the C-SiO2 interface enhanced phenol adsorption to promote the hydrogenation. Consequently, 100 % of phenol was hydrogenated to cyclohexanol at 60 °C within 30 min. Furthermore, the optimized catalyst exhibited high activity for phenol hydrogenation even after four reuse cycles. The outstanding stability of the catalyst and its requirement for mild reaction conditions favor its large-scale industrial applications.

Synthesis of Au/Ce2S3@CeO2/CuS nanocomposites for promoted catalytic performance in propargylamine conversion

A newly developed nanocomposite catalyst, Au/Ce2S3@CeO2/CuS, has been engineered for effective propargylamine synthesis through the A3 coupling reaction. The catalyst’s synthesis involved the targeted addition of 15 wt% CeO2 to the CuS sulfur precursor, leading to the formation of a Ce2S3 layer due to its lower solubility product constant (Ksp). This layer, along with 0.5 wt% Au nanoparticles, significantly increased the Ce3+ concentration (16.9 % to 33 %–52 %), which can accelerate the Cu+/Cu2+ valence state changes, thereby promoting the activation of the alkynyl hydrogen to enhance propargylamine formation. After 2 h reaction, the Au/Ce2S3@CeO2/CuS catalyst achieved over 99 % conversion, nearly 55 % more than pure CuS (45.5 %). The Au/Ce2S3@CeO2/CuS nanocomposite also showed excellent recyclability (80 % retention after 5 cycles) and a high conversion rate of 222.5 mmol·g−1·h−1.

Sustainable Formate Production via Highly Active CO2 Hydrogenation Using Porous Organometallic Polymer with Ru-PNP Active Sites.

Efforts to combine the advantages of homogeneous catalysts in terms of activity with the ease of separation process offered by heterogeneous catalysts continue to be actively pursued in the field of catalyst development. Heterogeneous catalysts were synthesized from Ru-MACHO organometallic compounds, recognized for their high hydrogenation catalytic activity linked to the active site of the Ru-PNP motif, through direct polymerization utilizing the Friedel-Crafts reaction. These catalysts were then applied for the conversion of greenhouse gas carbon dioxide (CO2) into formate via hydrogenation, exhibited with a record-high turnover frequency of 31,700 and a productivity of 36,100 kgformate/(kgcatalyst·d). Furthermore, the facile separation characteristics and recyclability of the heterogeneous catalysts were confirmed.

Structural design and electronic regulation of atomically dispersed Mo-S4 sites by second shell N species reconfiguration for intensifying hydrogen spillover

Intensifying hydrogen spillover by regulating the atomic local structures catalysts is crucial for improving the hydrogenation performance, but still hugely challenging. Herein, we report a robust single-atom catalyst featuring Mo-S4 sites in the first shell modulated with N atoms in the second shell (Mo-S4-N/C) by an efficient cyclodextrin supramolecular self-assembly pyrolysis strategy for intensifying hydrogen spillover in slurry-phase hydrocracking of vacuum residue (VR). We discovered that the H2 is activated at the single-atom Mo-S4 sites efficiently and the spillover of active hydrogen is accelerated by the reconfiguration of N species in the second shell. Remarkably, the Mo-S4-N/C catalyst demonstrates excellent catalytic hydrogenation activity with high turnover frequency calculated for total metals up to 0.46 s−1, the VR per pass conversion of 61 wt.%, liquid product yield of 94 wt.%, and the low coke content of 0.6 wt.%, along with good stability, respectively. Theoretical calculations revealed that the N species in the second shell regulated the electronic structure of Mo-S4 sites, promoting the migration of active hydrogen species by reducing the transfer energy barrier of hydrogen spillover, thus enhancing the hydrogenation performance. This work proposed a strengthened hydrogen spillover mechanism from the atomic scale for hydrogenation reaction, offering novel concepts for designing and developing high-performance hydrogenation catalysts.

Mo2Ti2C3TX MXene performance in catalytic CO2 hydrogenation and its promotion with single Pt atoms

Mo2Ti2C3Tx MXene materials, bare or loaded with strongly anchored single Pt atoms, were investigated using various methods, including STEM, XPS, XAS and DFT calculations. Upon Pt impregnation, the delaminated Mo-rich MXene surface undergoes partial oxidation, which is reversed by an H2 thermal treatment at 400 °C. The optimized MXene shows high catalytic activity for CO2 hydrogenation to CO and smaller amounts of methane and methanol. Around and above the pretreatment temperature of 400 °C, the MXene is gradually defunctionalized from O- and F-containing groups and depleted in carbidic carbon, leading to deactivation. Single Pt atoms are cationic after impregnation, and reduce upon H2 treatment, filling surface Mo vacancies. Pt addition increases the MXene activity, in particular by facilitating H2 dissociation, but has little effect on the single-atom catalyst selectivity and on the rate dependence upon reactant partial pressures. The lowest Pt loading leads to the highest turnover frequency, indicating that the MXene surface sites are key to CO2 activation.

Formic Acid-Intensified Photoreduction of NOx on Iron Minerals Triggers Daytime HONO Formation through Active Hydrogen.

Nitrous acid (HONO) is crucial in atmospheric chemistry as a precursor to morning peak hydroxyl radicals and significantly affects urban air quality by forming secondary pollutants, yet the mechanisms of its daytime formation is not fully understood. This study investigates the role of formic acid (HCOOH), a prevalent electron and proton donor, in the transformation of nitrogen oxides (NOx) and the formation of HONO on photoactive mineral dust. Exploiting hematite (Fe2O3) as an environmental indicator, we demonstrate that HCOOH significantly promotes the photoreduction of NO2 to HONO, while suppressing nitrate accumulation. This occurs through the formation of a surface ≡Fe-OOCH complex, where sunlight activates the C-H bond to generate and transfer active hydrogen, directly converting NO2 to HONO. Additionally, HCOOH can trigger the photolysis of nitrates as predeposited on Fe2O3, further increasing HONO production. These findings show that HCOOH-mediated photochemical reactions on iron minerals may contribute to elevated atmospheric HONO levels, highlighting a crucial pathway with broad effects on atmospheric chemistry and public health.

One-step green synthesis of Au@Pd concave nanocubes in deep eutectic solvents and their highly catalytic activities for selective hydrogenation

Concave nanomaterials possess superior properties, but their synthesis usually requires complicated steps, specific conditions and additional reagents (surfactants, capping agents, seeds, etc.). Herein, the well-defined Au@Pd concave nanocubes (CNCs) is facile one-step fabricated in a deep eutectic solvent (DES, named reline) composed of choline chloride (ChCl) and urea. It is found that the reline is crucial to the formation of Au@Pd CNCs. Owing to the concave core-shell structures, and electronic effects between Au core and Pd shell, Au@Pd CNCs exhibited excellent catalytic performance, and recovery convenience in the selective hydrogenation of 4-nitrostyrene. Specifically, under normal temperature and pressure conditions (25°C, 0.1 MPa), 4-nitrostyrene can be completely hydrogenated to 4-nitroethylbenzene within 7.0 min. After five cycles, Au@Pd CNCs still maintain the highly catalytic activity and 100 % selectivity toward 4-nitroethylbenzene. It is expected that well-constructed Au@Pd CNCs also display advanced potentials in other applications.

Exploring the synergistic benefits of biochar and gibberellic acid in alleviating cadmium toxicity

Cadmium (Cd) toxicity significantly threatens agricultural productivity and food safety. Developing effective strategies to enhance plant tolerance to Cd stress is essential. This study investigates the synergistic effects of biochar (BC) and gibberellic acid (GA3) on mitigating Cd toxicity in maize (Zea mays), focusing on their impact on oxidative stress markers and antioxidant enzyme activities. Soil samples were collected from the Cholistan Institute of Desert Studies (CIDS) and analyzed for trace metal ions and other properties. Biochar was produced from fruit and vegetable waste, washed, washed, deashed, and mixed with 10 ppm GA3. FH-1036 hybrid maize seeds were sterilized and planted in pots containing soil with varying Cd levels (0, 8, and 16 mg Cd/kg soil). Twelve treatments were established, including control, GA3, BC, and their combinations under different Cd stress levels. Plants were irrigated to maintain 60% field capacity and harvested at the V10 growth stage. Hydrogen peroxide (H2O2) contents and activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) were measured in roots, stems, and leaves. Statistical analysis was performed using OriginPro 2021, with ANOVA and Fisher’s LSD test used to determine significant differences. GA3 and BC treatments significantly reduced H2O2 levels in maize roots, stems and leaves under Cd stress. The combined treatment of GA3 + BC showed the most significant reduction in H2O2 levels across all plant parts, reducing root H2O2 by 50%, stem H2O2 by 55%, and leaf H2O2 by 53% under severe Cd stress (16 mg Cd/kg). SOD activity increased under non-stress conditions but decreased under Cd stress, with the highest activity observed in the combined treatment. POD activity followed a similar pattern, with GA3 + BC treatment resulting in the most significant increases under non-stress conditions and the least reductions under Cd stress. CAT activity showed substantial increases with GA3 + BC treatment, particularly under severe Cd stress, with a notable rise over the control. APX activity also exhibited enhancements with GA3 and BC treatments, especially in the combined treatment under various Cd stress levels. This study highlights the potential of combined BC and GA3 treatments in improving Cd stress tolerance in maize. Future research should focus on field trials and the long-term impacts of these treatments on crop productivity and soil health.

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

Semihydrogenation 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.

Selective hydrogenation of 5‐hydroxymethylfurfural to 5‐hydroxymethyltetrahydrofurfural over heterogeneous Pd catalyst under mild conditions

5‐Hydroxymethylfurfural (5‐HMF) derived from lignocellulose represents an important platform molecule that could be employed in the selective hydrogenation of the furan ring to prepare 5‑hydroxymethyltetrahydrofurfural (HMTHF). However, the reported catalytic systems for the synthesis of HMTHF using 5‐HMF still require additional hydrogen pressure. In this study, the Pd/ZrO2 catalyst with uniformly dispersed Pd nanoparticles was prepared via a simple impregnation reduction process. This catalyst exhibited excellent catalytic activity and selectivity for the hydrogenation of 5‐HMF to HMTHF. High HMTHF yield up to 92.3% was produced under mild reaction conditions of ambient hydrogen pressure and room temperature in methanol solvent. This result was superior to the most catalytic systems that had been reported so far. The mechanism study revealed that the active hydrogen species on the surface of the Pd nanoparticles and the reaction solvent in this study were the pivotal factors influencing the hydrogenation of furan rings in 5‐HMF.

Periodic polarity reversal triggered sequential electrochemical redox of blue TiO2 nanotube arrays for efficient removal of antibiotics and inorganic nitrogen from actual mariculture wastewater

Using blue TiO2 nanotube arrays (Ti/BTNAs) as both anode and cathode, a novel bipolar system that is suitable for operating in periodic polarity reversal (PR) and flow-through mode was established, aiming to effectively remove antibiotics and inorganic nitrogen from actual mariculture wastewater. Under optimal conditions of 4.0 mA/cm2 current density, 3.0 mL/min water flow rate and 2.0 cycles/h polarity reversal frequency, the PR-induced synergistic effect endows Ti/BTNAs abundant oxygen vacancies (20.53 %), high activity and extended service lifetime (5.25 years), realizing continuous production of surface-adsorbed active hydrogen (Hads∗) at cathode and reactive chlorine species (Cl, ClO, Cl2−, ClO−) over anode through Cl− reacting with reactive oxygen species (HO, SO4−, O2−) and ∼0.7 kWh/gTOC energy consumption. Bipolar system can also flexibly regulate denitrification mechanism through the PR-triggered sequential electrochemical redox of Ti/BTNAs in water flow direction, achieving minimum energy consumption of ∼43.4 ± 3.2 kWh/kg(NH4+-N) and 33.7 ± 2.3 % current efficiency. Berberine antibiotic degradation pathway was suggested by DFT calculations and LC-MS/MS analyses. This study provides a long-acting and low-consuming strategy for comprehensive treating mariculture wastewater.

First-principles thermodynamical modeling of molecular reactions on α-U(001) and α-UH3(001) surfaces and their influence on hydrogen activation

Density functional theory calculations coupled with thermodynamic analysis have been performed to investigate the reactions of hydrogen and impurity gases including O2, CO2, CO, N2 on α-U(001) and α-UH3(001) surfaces. Binding strength of adsorbates on α-UH3 is calculated to be weaker than α-U, suggesting enhanced poisoning-resistant properties of U-hydride compared to its metallic state. Surface phase diagrams of U under binary H2-O2, H2-N2 and H2-CO gaseous environments show that while N and C elements prefer to stay in their hydrogenated states on the hydride surface, isolated O atoms favorably interact with both α-U(001) and α-UH3(001), indicating the heavily poisoning effect of impurities containing oxygen. Global optimization of partially oxidized α-U(001) slabs induces surface geometry reconstruction and the activity of oxidized surfaces toward hydrogen adsorption can be linearly correlated with local electronic and atomic properties of the adsorption site.

Catalysts for Liquid Organic Hydrogen Carriers (LOHCs): Efficient Storage and Transport for Renewable Energy.

Restructuring the current energy industry towards sustainability requires transitioning from carbon based to renewable energy sources, reducing CO2 emissions. Hydrogen, is considered a significant clean energy carrier. However, it faces challenges in transportation and storage due to its high reactivity, flammability, and low density under ambient conditions. Liquid organic hydrogen carriers offer a solution for storing hydrogen because they allow for the economical and practical storage of organic compounds in regular vessels through hydrogenation and dehydrogenation. This review evaluates several hydrogen technologies aimed at addressing the challenges associated with hydrogen transportation and its economic viablity. The discussion delves into exploring the catalysts and their activity in the context of catalysts' development. This review highlights the pivotal role of various catalyst materials in enhancing the hydrogenation and dehydrogenation activities of multiple LOHC systems, including benzene/cyclohexane, toluene/methylcyclohexane (MCH), N-ethylcarbazole (NEC)/dodecahydro-N-ethylcarbazole (H12-NEC), and dibenzyltoluene (DBT)/perhydrodibenzyltoluene (H18-DBT). By exploring the catalytic properties of noble metals, transition metals, and multimetallic catalysts, the review provides valuable insights into their design and optimization. Also, the discussion revolved around the implementation of a hydrogen economy on a global scale, with a particular focus on the plans pertaining to Saudi Arabia and the GCC (Gulf Cooperation Council) countries. The review lays out the challenges this technology will face, including the need to increase its H2 capacity, reduce energy consumption by providing solutions, and guarantee the thermal stability of the materials.

Incorporation of TC4 (Ti-6Al-4V) to construct strong interfacial bonding with Mg matrix to achieve improved hydrogen storage kinetics

Effective contact between the catalyst and the Mg/MgH2 matrix is the key to efficiently enhancing the hydrogen storage kinetics. In this work, a Mg-10 wt% TC4 (Ti-6Al-4V) composite with strong interfacial bonding was prepared by vacuum hot pressing sintering, and the reinforcement mechanism of TC4 was investigated. The results indicated that TC4 has a significant improvement effect on the activation efficiency and hydrogen absorption/desorption kinetics. The hydrogen absorption and desorption activation energies of AZ91-TC4 (53.0/111.3 kJ/mol) are 19.6 and 37.2 kJ/mol lower than that of AZ91 without TC4, respectively. Moreover, TC4 can cause AZ91 to start dehydrogenation at 449 K, and the reduction is about 110 K. Except for the increase of grain boundaries and microcracks caused by TC4, the transition diffusion interface formed by TC4 and Mg matrix with a lower diffusion barrier can be used as a special fast diffusion channel to accelerate the hydrogenation process controlled by H atom diffusion. Meanwhile, the kinetic calculations indicate that the dehydrogenation process of AZ91 is controlled by the nucleation and growth step of Mg, and its nucleation activation energy is ca. 4 times the growth activation energy. TC4 and its induced precipitation of TiAl and Al8Mn5 can dramatically accelerate the nucleation process of Mg, resulting in the rate-determining step changing to the surface penetration of H atoms, and the desorption rate is significantly improved. These positive findings provide new tactics for designing excellent hydrogen storage catalysts.

Z-Scheme LaFeO3/Cd0.7Zn0.3S heterojunction based on 3DOM LaFeO3 perovskite for enhanced photocatalytic hydrogen activity

The narrow band gap semiconductor LaFeO3 with ABO3 perovskite structure has been deeply studied in the field of photocatalysis due to its good thermal stability, chemical stability, photoelectric properties and suitable band position. The inverse opal structure gives the material a large specific surface area and increases the adsorption area and active site of the catalyst. In this work, it is reported for the first time that perovskite LaFeO3 inverse opal was applied to photocatalytic hydrogen production. The Cd0.7Zn0.3S QDs were deposited on the skeleton wall of LaFeO3 inverse opal to construct LaFeO3/Cd0.7Zn0.3S binary heterojunction catalyst. The LaFeO3 3DOM can effectively increase the contact area with Cd0.7Zn0.3S QDs with an increase in specific surface area, and the multiple scattering effect improves the efficiency of light utilization. The introduction of Zn2+ ions regulate the band gap position of Cd0.7Zn0.3S QDs and increases the thermodynamic reduction ability of photo generated electrons. The Z-type heterojunction effect formed by LaFeO3 inverse opal and Cd0.7Zn0.3S QDs facilitates the separation and transmission of photo generated charges. The LaFeO3/Cd0.7Zn0.3S heterojunction catalysts achieved a hydrogen production performance of 277.48 μmol/g/h due to the large specific surface area of 3DOM, good light capture ability, band gap regulation of element doping, and efficient charge separation synergistic effect of heterojunction. This work provides new insights into the design and manufacture of perovskite-type 3DOM heterojunction photocatalysts.

Building organic-inorganic heterojunction NiCo2O4/h-BN toward artificial photosynthesis—Boron as hole

To convert CO2 and water into organic chemicals via photoelectrocatalytic (PEC) reduction of CO2 under mild conditions is considered to be one of promising methods to address a series of problems like climate change and energy crisis caused by over-emission of CO2. Herein, the organic-inorganic heterojunctions were designed and fabricated by using organic h-BN and inorganic NiCo2O4 as precursors. The optimal NiCo2O4@h-BN-6 heterojunction exhibited impressive performance in CO2 reduction, yielding C2+ chemicals with 100 % selectivity in a rate of 28.5 μM cm−2 h−1. This phenomenon is attributed to the structural feature of three active sites of nitrogen in a unique hexacycle like benzene, which benefit the carbon-carbon coupling among the intermediates. The first observed *N-H species suggest that the N sites can adsorb protons and electrons and convert them into highly active hydrogen atoms. The verification experiments demonstrate that the material will oxidize intermediates to acetic acid where boron atoms are presented as holes in semiconductor. The isotopic labeling experiments of 13CO2 and H218O verified that the products were derived from CO2 and water. The key active intermediates such as *CHO, *=CO, and *COCHO in the synthetic process of C2+ products had been confirmed by operando FTIR spectra and DFT calculations.

Hydration‐effect Boosted Active Hydrogen Facilitates Neutral Ammonia Electrosynthesis from Nitrate Reduction

AbstractElectrocatalytic nitrate reduction to ammonia (NO3RR) in a neutral medium is a green and effective strategy for treating nitrate pollution meanwhile producing ammonia. However, the insufficient active hydrogen (H*) on the catalyst surface resulting from the sluggish Volmer step (H2O → H+ + OH−), and the competitive hydrogen evolution reaction (HER) caused by H* coupling severely restrict the enhancement of NO3RR activity. Herein, a hydration‐effect boosted H*‐rich strategy facilitating neutral ammonia electrosynthesis from nitrate reduction is proposed. The introduction of the hydration‐effect‐promoting element aluminum into the copper‐based catalyst forming CuAlO2, which adjusts the electron density distribution in the catalyst system, and the resulting hydration‐effect significantly promotes the H* generation in a neutral medium. Moreover, the rapid charge transfer at the CuO/CuAlO2 interface facilitates the reaction kinetics and the H* diffusion. More importantly, the introduction of Al weakens the overly strong adsorption of intermediates by CuO, thereby accelerating the hydrogenation process and suppressing HER. Thus, under neutral conditions, CuO/CuAlO2 reached a Faradaic efficiency and an ammonia yield as high as 97.81 ± 1.94% and 10.21 ± 0.64 mg h−1 cm−2 at −1.0 V versus RHE toward NO3RR.

Pt/MgO catalysts intrinsically promoted by fast moving bed pyrolysis for hydrogenation properties

Elucidating the correlation between the geometric/electronic structure of the catalyst and its catalytic performance is of paramount importance. However, achieving precise manipulation over the geometric/electronic structure of the catalyst remains a formidable challenge. Here, we develop a fast moving pyrolysis bed (FMPB) strategy to finely regulate the geometry structure (Pt metal particle size and Pt-O coordination number (CN)) and electronic structure of the Pt/MgO catalyst. It is found that the hydrogen dissociation energy barrier is negatively related to the Pt atom electron density. The Pt1/MgO-600-N2 (600 and N2 represented the temperature and atmosphere under fast pyrolysis, respectively) with highest electron density exhibits the highest para-chloronitrobenzene (p-CNB) hydrogenation activity (66978 h−1), which is ∼220 times that of Pt nanoparticles (NPs, Pt NPs/MgO), ∼58 times that of Pt1/MgO-400-air, and ∼3 times that of Pt nanoclusters (NCs, Pt NCs/MgO). DFT calculations disclose that Pt1/MgO-600-N2 with highest Pt-5d center, which is more conducive to hydrogen dissociation. The transition of the H2 cleavage mode from homolytic (Pt NPs/MgO) to heterolytic (Pt1/MgO-600-N2) makes it more favorable for the hydrogenation of the polar nitro functional group, ensuring that substantial enhancement in its activity while preserving high selectivity in hydrogenation.