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This work reports a practical approach for C−O and C−C bond formation reactions catalysed by Pd nanoparticles supported on Luffa sponge (PdNPs@LS).PdNPs@LS were prepared via a green route in‐situ by using ethanol as solvent, and lignin content present in the luffa sponge could work as an effective reducing reagent to reduce Pd(II) to Pd(0) without any harsh chemical used for reduction. The bio‐based support used i. e. Luffa sponge extracted from the waste feedstock of Luffa guard in a simple filtration method is a cheap, biodegradable, abundant and renewable source with netting‐like three‐dimensional porous structure. Without significant loss of its activity the PdNPs@LS could be easily recovered and recycled for at least three times. The catalyst is characterized by FT‐IR, TGA, SEM‐EDX, TEM, and XPS analyses. [ABSTRACT FROM AUTHOR]

Co-B catalyst, W-modified Co-B (Co-W-B) catalyst, and Mo-modified Co-W-B (Co-W-Mo-B) catalyst powders were synthesized via chemical reduction of metal salt solutions at room temperature. The optimal hydrogen production rate was obtained when the ratio of the reducing agent (NaBH4) to the metal solution was 4:1. Among the ternary catalysts, the Co0.1-W0.9-B catalyst showed the optimal hydrogen production rate when the content of W doping was 0.9. Furthermore, the hydrogen production rate of the quaternary catalyst was enhanced when the content of Mo doping was 0.075, denoted as Co0.1-W0.9-Mo0.075-B. The catalyst powders were characterized by SEM, XRD, XPS, and BET. The hydrogen production rates of the Co-B catalyst, Co0.1-W0.9-B catalyst, and Co0.1-W0.9-Mo0.075-B catalyst were investigated for the decomposition of alkaline sodium borohydride (NaBH4) in a water–ethanol mixture solution. The Co0.1-W0.9-Mo0.075-B catalyst exhibited the highest hydrogen production rate compared to Co-B and Co0.1-W0.9-B catalyst powders. The optimal hydrogen production rate of the Co0.1-W0.9-Mo0.075-B catalyst is 4600 ml·min−1·g−1, which is nearly 1.9 times higher than that of the Co-B catalyst. Moreover, the Co0.1-W0.9-Mo0.075-B catalyst exhibited good stability, retaining 73% of its catalytic activity after five cycles, and had a low apparent activation energy of 41.51 kJ·mol−1. [ABSTRACT FROM AUTHOR]

Molybdenum‐ or tungsten‐dependent formate dehydrogenases have emerged as significant catalysts for the chemical reduction of CO2 to formate, with biotechnological applications envisaged in climate‐change mitigation. The role of Met405 in the active site of Desulfovibrio vulgaris formate dehydrogenase AB (DvFdhAB) has remained elusive. However, its proximity to the metal site and the conformational change that it undergoes between the resting and active forms suggests a functional role. In this work, the M405S variant was engineered, which allowed the active‐site geometry in the absence of methionine Sδ interactions with the metal site to be revealed and the role of Met405 in catalysis to be probed. This variant displayed reduced activity in both formate oxidation and CO2 reduction, together with an increased sensitivity to oxygen inactivation. [ABSTRACT FROM AUTHOR]

The transition-metals carbon catalysts belong to intensively studied alternatives to the Pt-based catalysts promoting the oxygen reduction reaction (ORR) in electrochemical fuel cells (FCs). Commonly studied Fe,Co–N–C composites are usually obtained through pyrolysis and used as such or after a chemical post-treatment with an oxidizing agent. This treatment is applied to remove inactive metal species, thus, promoting the electrochemical activity. The impact of an oxidizing agent is poorly addressed in the literature, while its nature may negatively affect the catalyst's performance. Herein we report the first comparative study on the effect of post-treatment with the most common oxidizing agents such as HCl, HNO 3 , H 2 SO 4 and H 2 O 2 , on the structural and electrochemical properties of the Fe,Co–N–C catalyst. The catalyst is made by pyrolysis of the Co,Zn-ZIF metal-organic framework enriched with iron and nitrogen. Its structure was observed withstanding the action of mineral acids but suffers from hydrogen peroxide. The treatment with either nitric or chloric acid may improve the electrochemical performance up to 4%, while other agents decrease that by 6% and slow down the ORR rate. These findings are useful for the careful design of post-treatment procedures for carbon catalysts. • The Fe,Co–N–C carbon-based catalyst was obtained from Fe,Co-ZIF-8 MOF via pyrolysis at 700 °C in an inert atmosphere. • The Fe,Co–N–C catalyst was treated with four oxidizing agents - chloric, nitric and sulfuric acids, and hydrogen peroxide. • Structural and compositional changes were assessed with multi-technique characterization of the catalysts. • The catalysts treated with nitric and chloric acids demonstrated improved performance for ORR in an acidic medium. [ABSTRACT FROM AUTHOR]

The development of high-efficient and low-cost catalysts is crucial for promoting KBH 4 hydrolysis to produce hydrogen. Herein, ZIF-67 supported cobalt-molybdenum-nickel based boride (Co–Mo–Ni–B/ZIF-67) nanocomposites with dandelion-like morphology were designed as catalysts of KBH 4 hydrolysis reaction and were synthesized via the chemical reduction process. Moreover, the element ratio and the loading amount of Co–Mo–Ni–B were optimized, and effects of KBH 4 concentration, KOH concentration, and reaction temperature on catalytic performances were studied. As expected, ZIF-67 substrate avoids the agglomeration of amorphous Co–Mo–Ni–B, and the synergy between ZIF-67 and uniformly dispersed Co–Mo–Ni–B active substances accelerates hydrogen generation rate. As a result, the maximum hydrogen generation rate of 17400 mL min−1 g−1 is achieved with the optimized KOH concentration of 10% and KBH 4 concentration of 6% at the reaction temperature of 30 °C. In addition, Co–Mo–Ni–B/ZIF-67 exhibits moderate durability performance with a cyclic retention rate of 51.9 % after five cycles. This dandelion-like structure design provides an idea for the development of efficient catalyst for hydrolysis of borohydrides. [Display omitted] • Co–Mo–Ni–B/ZIF-67 is prepared as catalysts of KBH 4 hydrolysis reaction. • The dandelion-like structure of Co–Mo–Ni–B/ZIF-67 exhibits excellent catalytic performance. • Co–Mo–Ni–B/ZIF-67 with optimized composition displays the hydrogen generation rate of 17400 mL min−1 g−1 at 30 °C. • ZIF-67 substrate avoids the agglomeration of amorphous Co–Mo–Ni–B. [ABSTRACT FROM AUTHOR]

The process of hydrolysis of sodium borohydride is a new and clean method for the production of hydrogen. In this study, cobalt nanoparticles were synthesized by the mechanochemical and chemical reduction methods, and their catalytic performance was compared. The effect of using different cobalt precursors and reducing agents was investigated for the sample prepared via the chemical reduction method. The results showed that the cobalt catalysts synthesized through the chemical reduction method possessed better catalytic performance. Also, the sample prepared using cobalt nitrate and sodium borohydride had a higher hydrogen generation rate (HGR), which was equal to 3272.7 ml min−1g−1. The kinetics of the cobalt catalyst in the process have also been investigated, revealing that the rate of hydrogen production is dependent on the concentrations of sodium borohydride and sodium hydroxide, the catalyst dosage, and the process temperature. The crystal size of this catalyst was 21.6 nm with spherical agglomerated particles. The BET area of the best sample and its activation energy was equal to 11.18 m2g-1 and 22.3 kJmol-1, respectively. This catalyst was also stable in successive cycles. [Display omitted] • Cobalt catalysts were synthesized via the mechanochemical and chemical reduction methods. • The catalytic performance of the cobalt catalyst in the hydrolysis of NaBH 4 was high. • The hydrogen generation rate of the Co–B catalyst was 3272.7 mLmin−1g−1 at 30 °C. • The activation energy of the Co–B catalyst is lower compared to that of other cobalt-based catalysts. [ABSTRACT FROM AUTHOR]

The efficient conversion of CO2 to value‐added products represents one of the most attractive solutions to mitigate climate change and tackle the associated environmental issues. In particular, electrochemical CO2 reduction to fuels and chemicals has garnered tremendous interest over the last decades. Among all products from CO2 reduction, formic acid is considered one of the most economically vital CO2 reduction products. P‐block metals (especially Bi, Sn, In, and Pb) have been extensively investigated and recognized as the most efficient catalytic materials for the CO2 electroreduction to formate. Despite remarkable progress, the future implementation of this technology at the industrial‐scale hinges on the ability to solve remaining roadblocks. In this review, the current research status, challenges, and prospects of p‐block metal‐based catalysts primarily for CO2 electroreduction to formate are comprehensively reviewed. The rational design and nanostructure engineering of these p‐block metal catalysts for the optimization of their electrochemical performances are discussed in detail. Subsequently, the recent progress in the development of state‐of‐the‐art operando characterization techniques together with the design of advanced electrochemical cells to uncover the intrinsic catalysis mechanism is discussed. Lastly, a perspective on future directions including tackling critical challenges to realize its early industrial implementation is presented. [ABSTRACT FROM AUTHOR]

The efficient conversion of CO2 to value‐added products represents one of the most attractive solutions to mitigate climate change and tackle the associated environmental issues. In particular, electrochemical CO2 reduction to fuels and chemicals has garnered tremendous interest over the last decades. Among all products from CO2 reduction, formic acid is considered one of the most economically vital CO2 reduction products. P‐block metals (especially Bi, Sn, In, and Pb) have been extensively investigated and recognized as the most efficient catalytic materials for the CO2 electroreduction to formate. Despite remarkable progress, the future implementation of this technology at the industrial‐scale hinges on the ability to solve remaining roadblocks. In this review, the current research status, challenges, and prospects of p‐block metal‐based catalysts primarily for CO2 electroreduction to formate are comprehensively reviewed. The rational design and nanostructure engineering of these p‐block metal catalysts for the optimization of their electrochemical performances are discussed in detail. Subsequently, the recent progress in the development of state‐of‐the‐art operando characterization techniques together with the design of advanced electrochemical cells to uncover the intrinsic catalysis mechanism is discussed. Lastly, a perspective on future directions including tackling critical challenges to realize its early industrial implementation is presented. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of CO2 into chemical feedstocks has been regarded as an attractive way to reconstruct the carbon cycle. In this work, nitrogen‐doped carbon was prepared by high temperature pyrolysis using polydopamine (PDA) microspheres as precursors. The effects of doped nitrogen units, surface hydrophilicity and pore structures of the N‐Carbon catalysts on the CO2 reduction reaction (CO2RR) activities were systematically investigated. It was demonstrated that the competition between the hydrogen evolution reaction (HER) and the CO2RR under reduction potentials was modified by the nature of surface hydrophilicity/hydrophobicity and the doped nitrogen units. The CO2RR activities were further optimized via the pore structures regulation. Results showed that pore structure with size below 1 nm was favorable for CO2RR and the developed N‐Carbon catalysts with optimized nitrogen units, hydrophilicity, and pore structure achieved a high CO2 to CO Faradaic efficiency of 95 % in the H‐cell. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrogen spillover induced a cooperative catalysis between Pd particles and Pd single atoms supported on carbon supports. • Few-layer graphene (FLG) support allows more extended H-spillover than multi-walled carbon nanotubes (CNT) • Pd/FLG is more active for solvent-free total hydrogenation of squalene than Pd/CNT but deactivated. • A new mechanism of thermal catalyst deactivation induced by H-spillover is proposed. General interest in solvent-free catalytic processes is driven by the development of environmentally and economically acceptable procedures. Such processes require the use of highly active and stable catalysts. This study reports on the synthesis, characterization, and kinetic evaluation of two highly active Pd catalysts supported on different carbons support, i.e., multi-walled carbon nanotubes (CNT) and few-layer graphene (FLG). These catalysts, with similar Pd loading (∼2 wt%) and containing both Pd single atoms (Pd SA) and nanoparticles (Pd NP), were systematically tested for solvent-free total hydrogenation of squalene (SQE) to obtain high-purity squalane (SQA). Thanks to the unique cooperative catalysis between Pd SA and Pd NP involving H-spillover, the activities of both catalysts were high compared to catalysts described in the literature. Solvent-free total hydrogenation of SQE could be performed under mild conditions (120 °C, 20 bar H 2 , 4 h) using ultralow Pd loading (60 ppm). However, since this reduction reaction is highly exothermic (ΔH R = − 765 kJ.mol−1), heat management during the reactor operation with these highly active catalysts is crucial to avoid deactivation and thermal runaway. Under these conditions, Pd/FLG was highly active but deactivated, unlike Pd/CNT, which still has high activity, but does not deactivate. Characterizations (ICP, XPS, Raman, TPD-MS, HAADF-STEM) of the Pd/FLG catalyst before and after reaction, supported by calculations based on density functional theory, allowed us to propose a new mechanism of catalyst deactivation involving the chemical reduction of specific surface oxygen groups of the carbon support induced by H-spillover. [ABSTRACT FROM AUTHOR]

Electrochemical ammonia synthesis from N 2 under mild condition is considered a promising strategy to store energy produced by renewable sources, but it is affected by the lack of efficient catalysts for nitrogen reduction. In this work Fe-based nanoparticles with different morphology are deposited on carbon cloth via drop-casting and chemical reduction. The catalyst activity has been evaluated by cyclic voltammetry and chronoamperometry, using a 0.01 M phosphate buffered electrolyte (PBS). The produced ammonia has been determined through the indophenol method. As effective strategy to improve the catalytic activity, the morphology and particle size have been optimized and an electrochemical activation procedure has been implemented. Activation increases the available active sites and is related to higher amount of oxygen vacancies and Fe+2/Fe+3 ratio. Catalysts with optimized morphology produce ammonia at −0.35 V vs RHE with yield of 26.44 μg mg cat −1h−1 and Faradaic efficiency of 20.4%, more than five times higher than without activation. [Display omitted] • Fe-based NPs are deposited by drop casting and chemical reduction on C-cloth substrates. • Particles morphology has been optimized. • The catalytic activity for Nitrogen electroreduction reaction was investigated. • A crucial role is played by the oxygen vacancies and by the Fe+2/Fe+3 ratio. • The ammonia yield with the optimized catalyst was 5 times higher than without optimization. [ABSTRACT FROM AUTHOR]

The exploitation of economical and high‐efficient heterogeneous catalysts plays a vital role in ammonia‐borane (NH3BH3, AB) hydrolysis for hydrogen evolution. Herein, poly(N‐vinyl‐2‐pyrrolidone) (PVP) stabilized highly dispersed Ru–Ni nanoclusters immobilized on reduced graphene oxide (rGO) are successfully synthesized via in situ chemical reduction. The optimized Ru1Ni1@PVP/rGO‐1 catalyst exhibits a superior catalytic performance toward hydrolytic dehydrogenation of AB for hydrogen evolution, with a low activation energy (Ea) of 21.1 kJ mol−1 and a high turnover frequency (TOF) value of 425.1 molH2 molRu−1 min−1at 298 K. Moreover, an outstanding recyclability with 82.1% of the initial catalytic activity is achieved after 20 consecutive cycles due to PVP coating that can effectively prevent the agglomeration of nanoclusters during the recycling tests. Experimental analyses and DFT calculations reveal a synergistic effect in Ru–Ni nanoclusters, resulting in a strong adsorption of AB molecules and an easy activation of water molecules on Ru–Ni nanoclusters. These findings in this study open a new avenue for a hopeful design of highly efficient heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

The photocatalytic CO2 reduction into value‐added chemicals is regarded as one promising technology to mitigate environmental issues and the energy crisis of the modern world due to the extended CO2 emissions. Recent advances have shown that iron porphyrins are considered as one of the most efficient molecular catalysts in the activation and reduction of molecules like CO2. Thus, a suitably modified FeIII porphyrin ([FeIII(TF4TMAP)](CF3SO3)5) was prepared and its catalytic activity in terms of photocatalytic reduction of CO2 was studied. This iron catalyst possesses four fluorine substituents in the ortho and the meta position of each meso‐phenyl group of the porphyrin, while trimethylammonium groups were placed in the para position. Photocatalytic studies were performed in the presence of an iridium complex as a chromophore and have shown that [FeIII(TF4TMAP)](CF3SO3)5 can effectively reduce CO2, achieving excellent turnover numbers (up to 5500 TONs) and high turnover frequencies. The main reduction product of this photocatalytic system was CO, and only a small amount of hydrogen was detected, presenting a maximum selectivity of 86 % for CO. [ABSTRACT FROM AUTHOR]

Oxygen reduction reaction (ORR) is a very important reaction that occurs at the cathodic side in proton exchange membrane fuel cells (PEMFCs). The high cost associated with frequently used Pt-based electrocatalysts for ORR limits the commercialization of PEMFCs. Through bifunctional and electronic effects, theoretical calculations have proved that alloying Pt with a suitable transition metal is likely to improve ORR mass activity when compared to Pt-alone systems. Herein, we demonstrate the preparation of bimetallic Pt–Fe nanoparticles supported on reduced graphene oxide sheets (RGOs) via a simple surfactant-free chemical reduction method. The present method produces PtFe/RGO catalyst particles with a 3.2 nm diameter without agglomeration. PtFe/RGO showed a noticeable positive half-wave potential (0.503 V vs. Ag/AgCl) compared with a commercial Pt/C catalyst (0.352 V vs. Ag/AgCl) with minimal Pt-loading on a glassy carbon electrode. Further, PtFe/RGO showed a higher ORR mass activity of 4.85 mA/cm2-geo compared to the commercial Pt/C (3.60 mA/cm2-geo). This work paves the way for designing noble−transition metal alloy electrocatalysts on RGO supports as high-performance electrocatalysts for ORR application. [ABSTRACT FROM AUTHOR]

Supported Pt catalysts play an important role in selective hydrogenation reactions for upgrading bio-derived chemicals, and they are traditionally prepared by methods such as deposition–precipitation (DP), wet impregnation (WI) and chemical reduction (CR) using NaBH4 and H2 under thermal conditions. This study developed a new reduction method to produce supported Pt NPs on nanofibers, in which Ti3AlC2 (a typical MAX phase) and chloroplatinic acid (H2PtCl6) were employed as raw materials, using as-produced H2 as a reducing agent under hydrothermal synthetic conditions. In the selective hydrogenation of furfural to furfuryl alcohol, the newly-developed catalyst of Pt2.0/Ti3AlxC2Ty exhibited high furfural (FUR) conversion (86.3%) and excellent furfuryl alcohol (FA) selectivity (98.1%) under optimized reaction conditions of 600 rpm, 100 °C, 3 h, and 1 MPa H2 in aqueous media. Moreover, these fibrous catalysts exhibited strong reusability and recyclability for five runs without loss of activity and selectivity. [ABSTRACT FROM AUTHOR]

Sodium borohydride (NaBH4) is considered a good candidate for hydrogen generation from hydrolysis because of its high hydrogen storage capacity (10.8 wt%) and environmentally friendly hydrolysis products. However, due to its sluggish hydrogen generation (HG) rate in the water, it usually needs an efficient catalyst to enhance the HG rate. In this work, graphene oxide (GO)-modified Co-B-P catalysts were obtained using a chemical in situ reduction method. The structure and composition of the as-prepared catalysts were characterized, and the catalytic performance for NaBH4 hydrolysis was measured as well. The results show that the as-prepared catalyst with a GO content of 75 mg (Co-B-P/75rGO) exhibited an optimal catalytic efficiency with an HG rate of 12087.8 mL min−1 g−1 at 25 °C, far better than majority of the findings that have been reported. The catalyst had a good stability with 88.9% of the initial catalytic efficiency following 10 cycles. In addition, Co-, B-, and P-modified graphene showed a synergistic effect improving the kinetics and thermodynamics of NaBH4 hydrolysis with a lower activation energy of 28.64 kJ mol−1. These results reveal that the GO-modified Co-B-P catalyst has good potential for borohydride hydrolysis applications. [ABSTRACT FROM AUTHOR]

Electrochemical hydrogenation is an environmentally favorable alternative to chemical reduction of indigo because it performs under ambient conditions using water as the donor of hydrogen. The purpose of this work is to fabricate electrocatalysts with high activity and durability for electrocatalytic hydrogenation of indigo. This work compares the performances of a series of Ni based catalysts (Ni, NiMo, NiP and NiMoP) on the substrate of carbon felt (CF) for electrolyzing water. Both the overpotential and Tafel slop are decreased as a function of the components as Ni > NiMo > NiP > NiMoP. Hence, NiMoP/CF shows the excellent performance based on the thermodynamics (η 10 = 239 mV) and kinetics (Tafel slope = 89.7 mV·dec−1) for splitting water. Further, the electrode of NiMoP/CF was used for the electrocatalytic hydrogenation of indigo. The conversion efficiency and Faradic efficiency can be improved as 26.2% and 10.7% respectively. Furthermore, the dyeing behavior of the electrohydrogenated indigo is similar to that of conventional reduction methods. Thus, the present work offers foundational results and paves the way for the design of new catalytic materials for the reduction of vat dyes. [Display omitted] • Electrodeposited NiMoP/CF for HER was explored systematically. • NiMoP/CF shows the better thermodynamics and kinetics of HER. • NiMoP/CF was evaluated as a stable and active electrocatalyst for the ECH of indigo. • NiMoP/CF shows the higher efficiency of conversion and Faraday of ECH of indigo. [ABSTRACT FROM AUTHOR]

In this study, TiO2-supported Ni-Mo-Ru–B (TiO2@Ni-Mo-Ru–B) catalyst was synthesized by chemical reduction method for hydrogen production from the hydrolysis of potassium borohydride (KBH4) solution. The characterizations of the synthesized catalysts were carried out with BET, XRD, and SEM. In hydrolysis experiments, the effects of parameters such as KOH concentration, KBH4 concentration, catalyst amount, metal/TiO2 ratio, and temperature on hydrogen production rate were investigated. The optimum metal/TiO2 ratio was determined as 10% and the hydrogen production rate of the catalyst at 30 °C was calculated as 2410.28 mL/min.gcat. In addition, the reaction rate order was found to be 0.8 (nth order); accordingly, the value of the activation energy was obtained from the Arrhenius equation as 51.807 kJ/mol. [ABSTRACT FROM AUTHOR]

The selective chemical conversion of biomass components to useful bioproducts may contribute to a renewable resource-based economy. The selective production of target bioproducts may be accomplished using heterogeneous catalysts operating under relatively moderate reaction conditions. In this work, carbohydrate biomass derived α-angelica lactone (AnL) and levulinic acid (LA) were converted to the versatile bioproduct γ-valerolactone (GVL), in the presence of nanohybrid catalysts (M-FDCA) and the microcrystalline metal-organic framework CAU-28, all of which were synthesized from bio-based 2,5-furandicarboxylic acid (FDCA) and a metal (M = Zr or Hf) precursor. The nanohybrids were prepared in a simple fast (FT) fashion, and, for comparison, via a conventional solvothermal (S) procedure. The M-FDCA catalysts stood on a higher footing than CAU-28 in the conversion of AnL and LA to GVL. The superior results for the M-FDCA catalysts may be partly due to their higher ratio S ext :S BET and nano-features, which may advantageously enhance active sites accessibility. In particular, the Hf-FDCA catalysts were stable and performed superiorly to the Zr-FDCA ones. Experimental mechanistic studies shed light on the multifunctional behavior of the hybrid catalysts in the one-pot conversion of AnL-to-GVL, which involved acid and reduction chemistry. [Display omitted] • Fast synthesis of biobased 2,5-furandicarboxylic acid (FDCA), Zr and Hf nanohybrids. • Catalyst benchmarking with microcrystalline metal-organic framework CAU-28. • Hf-FDCA best-performing in one-pot conversion of angelica lactone to γ-valerolactone. • Catalyst multifunctionality associated with -COOH of the linker and metal sites. • Hf-FDCA also best performing for levulinic acid to γ-valerolactone in 2-butanol. [ABSTRACT FROM AUTHOR]

As ideal cathode catalysts for proton exchange membrane fuel cells (PEMFCs), the oxygen reduction reaction (ORR) activity and durability of Pt‐based alloys can be improved further. This study presents the catalyst with Au doping on the surface of an ordered PtFe alloy (Au‐PtFe/C) utilizing a synergistic process of microwave reduction and chemical replacement, as well as the reorganization of a Pt‐rich surface using acid etching and high temperature annealing. Physical characterization indicated that the oxygen binding energy on the surface of Au‐PtFe/C was more effective at promoting the ORR reaction than commercial Pt/C, which contributes significantly to its enhanced activity. Further electrochemical tests revealed that the Au‐PtFe/C catalyst exposes abundant active sites for ORR, with mass and specific activity up to 12 and 8 times that of commercial Pt/C, respectively. Additionally, the catalyst demonstrated remarkable durability following 10,000 cycles of accelerated durability tests (ADT) in acidic circumstances. In PEMFC test, the single cell with an Au‐PtFe/C cathode also performed admirably when compared with commercial Pt/C. Owing to its facile synthesis, low cost, and exceptional performance, this bimetal‐doped ordered Pt‐based alloy has the capability to be a promising component in fuel cells commercialization. [ABSTRACT FROM AUTHOR]

[Display omitted] In this work, pristine and NaBH 4 etched CeO 2 nanorods supported ruthenium (Ru) catalysts were synthesized and employed to investigate the effects of chemical etching and reduction activation treatment on CO oxidation. With 1 wt% Ru loading, the CeO 2 nanorods supported catalyst samples, after 6 wt% NaBH 4 etching treatment, showed significantly promoted H 2 consumption under 100 °C and low apparent activation energy (i.e., E a ∼ 31.2 kJ/mol) for CO oxidation. In - situ CO-DRIFTS profiles revealed that, for the reduced sample, the observed CO adsorption at ∼ 2020 cm−1 at 40 °C may be related to a strong RuO x -CeO 2 interaction induced by the NaBH 4 etching treatment, which was supported by the oxygen vacancy analysis results of X-ray photoelectron spectroscopy and CO-temperature programmed desorption. The enriched surface defects on CeO 2 support due to the chemical etching and reduction treatments are believed to promote the interaction between RuO x species and CeO 2 , which is responsible for the enhanced activity of CO oxidation. [ABSTRACT FROM AUTHOR]

The construction of binary metal Pd‐based catalysts is an effective strategy to enhance the activity of methanol oxidation reaction. Herein, atomically dispersed Ir single atoms doped to cuboctahedral Pd nanoparticles (Ir‐SAs/Pd) as efficient catalysts for alkaline methanol oxidation are prepared via a simple chemical reduction method. The synthetic Ir‐SAs/Pd catalysts exhibit the outstanding mass activity of about 1717.3 mA mgPd−1 compared with pure Pd and commercial Pd/C in electrooxidation for methanol. Meanwhile, the introduction of Ir single atoms enhances the CO tolerance of Pd nanoparticles to a large extent. On the basis of density functional theory results, the enhanced catalytic performance and CO tolerance rely on the effective improvement of the electron dominance near Fermi level and the negative shift of the d‐band center for Pd as a result of the electron redistribution between Pd and Ir atoms. This article will provide new insight into the design of high‐performance binary metal catalysts for methanol oxidation in alkaline media. [ABSTRACT FROM AUTHOR]

The present work describes the electrocatalytic reduction of dioxygen using polymerized Co-4-pyridylporphyrin in presence of electrochemically reduced graphene oxide. The polymeric porphyrin was synthesized by following the metalation procedure using the solvent system CHCl 3 –CH 3 OH. The electrocatalyst and the materials for comparison were synthesized by electrochemical as well as chemical reduction of graphene oxide either in the presence or in the absence of porphyrin. These materials were characterised by XPS, SEM, HR-TEM, Raman spectral and EIS techniques. The studies on the kinetics of ORR using rotating disk electrode showed the reduction through a 4-electron pathway under alkaline conditions. [Display omitted] • Coordination polymer of cobalt-4-pyridylporphyrin. • Composites of graphene oxide and polymeric porphyrin. • ORR using electrochemically reduced GO and polymerized cobalt-4-pyridylporphyrin. • 4-electron reduction of dioxygen. • Activity of the prepared electrocatalyst in ORR in presence of methanol. [ABSTRACT FROM AUTHOR]

Developing high-activity catalysts for the hydrolysis of ammonia borane (NH 3 BH 3 ; AB) is a crucial and urgent task, which is presently considered an effective strategy for hydrogen generation in the applications of portable proton exchange membrane fuel cells (PEMFCs). In this study, carbon nanotubes (CNTs) were modified by self-growth of metal-organic frameworks (MOFs) on their surfaces. As self-sacrificial templates, the carbonization of cobalt and nitrogen containing MOFs led to the modification of CNT. Subsequently, cobalt was transformed into cobalt phosphide (Co 2 P) via phosphatization to form Co 2 P/N co-decorated CNTs (NCP-CNTs). Ru/NCP-CNT catalysts were obtained by loading ruthenium nanoparticles (NPs) using a chemical reduction method and their catalytic performance for H 2 production via the hydrolysis of AB was systematically investigated. Ru/NCP-CNTs exhibited excellent catalytic activity, with an initial high turnover frequency (TOF) of 193.9 mol H2 ·mol Ru −1·min−1 and a low activation energy of 32.4 kJ·mol−1. The incorporation of Ru NPs and their excellent synergistic effect with the NCP-CNT supports can explain the improved performance. This work provides an updated approach for fabricating low-cost and high-efficiency catalysts for the hydrolysis of AB. • The Ru/NCP-CNT catalysts were successfully prepared. • Ru/NCP-CNT exhibited superior catalytic activity toward AB hydrolysis. • Low E a of 32.4 kJ·mol−1 and high TOF of 193.9 mol H2 ·mol Ru −1·min−1 were achieved. • Synergistic effect between Ru NPs and NCP-CNT was responsible for the improved performance. [ABSTRACT FROM AUTHOR]

• Based on the constant potential implicit solvent model, a realistic electrocatalytic environment was simulated. • The ORR activity of S-coordinated FeN 4 was simulated using a constant potential implicit solvent model. • It was found that FeN 4 S2 exhibited the highest activity under -2e conditions with an overpotential of 0.39V. • The high electronegativity of S enhances the valence state of Fe, weakens adsorption of *OH, and promotes the ORR process. The widespread application of S doping in Fe-N-C materials aims to enhance the catalytic activity for oxygen reduction reactions (ORR). However, the current doping strategies are primarily centered on the first coordination layer encompassing Fe atoms. Consequently, this study employs first-principles calculations to compute the formation and binding energies of FeN 4 doped with S atom. It further delves into the influence of diverse doping sites on catalyst stability and meticulously analyzes the configurations and corresponding ORR activities of four catalysts, namely FeN 4 S-N (Number=0∼3), utilizing a constant-potential implicit solvent model to simulate authentic electrocatalytic environments. The findings reveal that under vacuum conditions, FeN 4 S1 exhibits the utmost ORR activity, boasting a potential of 0.53 V. Conversely, within the constant-potential implicit solvation model, FeN 4 S2 emerges as the catalyst with the highest ORR activity, achieving a potential of 0.39 V. Therefore, calculations leveraging the constant-potential solvation model offer more realistic insights into catalyst design, thereby guiding the development of superior catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of high-performance, low cost and earth abundant catalysts for hydrogen evolution reaction (HER) is desired. This work presents amorphous CoFeB supported on nickel foam (NF), prepared by a facial chemical reduction method, as an active catalyst for HER in alkaline solution. Structure characterization indicated that with the incorporation of Fe atom, CoFeB catalysts exhibit similar petal-like granular morphology as CoB. The optimal CoFeB/NF-0.15 catalyst exhibits Brunauer-Emmett-Teller (BET) surface area of 27.4 m2 g−1, nearly two times larger than 13.2 m2 g−1 for CoB, suggesting higher specific surface area. CoFeB/NF-0.15 catalyst shows excellent HER performance and reaches −10 mA cm−2 at overpotential of 35 mV in alkaline solution, and Tafel slope of 84.7 mV dec−1, indicative of Volmer-Heyrovsky reaction mechanism. The synergistic effect among Fe, Co and B atoms and the more exposed active sites as well as faster electron transfer kinetics collectively contributed to the improved intrinsic activity of CoFeB for HER. Moreover, CoFeB/NF-0.15 exhibits good stability for over 16 h. • CoFeB was fabricated on nickel foam by a facile reduction method. • CoFeB shows a petal-like granular morphology. • The CoFeB/NF exhibited high HER activity in 1.0 M KOH solution. • The as-prepared catalyst was proved to be stable upon long-term electrolysis. [ABSTRACT FROM AUTHOR]

In this work, via the method of wet impregnation and chemical reduction, low-cost and available bentonite modified by cetyltrimethylammonium bromide (CTAB) was utilized as support to synthesize a novel organobentonite-supported Pd composite catalyst used for the catalytic transfer hydrogenation (CTH) of polyunsaturated fatty acid methyl ester (FAME). According to the results of characterization analysis, the organic modifier of CTAB was intercalated into the interlayer of bentonite, and the active metal Pd was immobilized and uniformly dispersed in the prepared composite catalyst. The possible formation mechanism of composite catalyst was proposed. The synthesized composite catalyst presented higher hydrogenation activity and selectivity compared with the pure nano-Pd catalyst. Moreover, the excellent stability remained for the composite catalyst after five catalytic runs in FAMEs hydrogenation. Hence, bentonite, as an economical and promising feedstock, could be used to synthesize a high-efficient and stable supported Pd composite catalyst successfully for the CTH of FAME. Low-cost bentonite, used as raw material, was modified by cetyltrimethylammonium bromide (CTAB) through the cation exchange process, forming organobentonite (OB) with an increased interlayer spacing. The cations of CTAB might be absorbed into the interlayers and on the surface of bentonite. The Pd ions were introduced through the impregnation of precursor solution of Pd (H2PdCl4) and bound to the cations of CTAB via electrostatic interactions. After the chemical reduction process by using NaBH4, the anionic PdCl42− could be reduced to metal Pd, which was immobilized and dispersed in the interlayers and on the surface of organobentonite, and then a novel Pd/OB composite catalyst formed. According to the result of TEM measurement, Pd particles showed the spheroidal shapes and dispersed uniformly in the synthesized composite catalyst. [ABSTRACT FROM AUTHOR]

Stereoselective hydrogenation of α‐pinene over heterogenous catalysts under solvent‐free conditions is promising for biomass conversion but challenging. Herein, we prepared the Ru‐NiO/Hβ catalysts using chemical reduction and galvanic replacement methods. With the increase of Ni content, the selectivity of cis‐pinane was significantly improved. A high conversion of 100 % and a high cis‐pinane selectivity of 98 % were achieved after 4 h reaction at 80 °C. It has been verified that the addition of Ni can adjust the ratio of Brønsted and Lewis acid, regulate the hydrogen spillover between Ru and support, change the adsorption site of substrate and form steric hindrance effect. All these contribute to the better selectivity of the catalyst. In addition, catalysts presented good stability in the 900 h test. [ABSTRACT FROM AUTHOR]

The preparation of Ru nanoparticles supported on γ-Al2O3 followed by chemical reduction using RuCl3 as a precursor is demonstrated, and their properties are compared to Ru nanoparticles supported on γ-Al2O3 prepared by impregnation of γ-Al2O3 with Ru3(CO)12 and subsequent thermal decomposition. The Ru nanoparticles resulting from chemical reduction of RuCl3 are slightly larger (1.2 vs. 0.8 nm). In addition, Ru nanoparticles were deposited on Stöber SiO2 using both deposition techniques. These particles were larger than the ones deposited on γ-Al2O3 (2.5 and 3.4 nm for chemical reduction and thermal decomposition, respectively). Taking into account the size differences between the Ru nanoparticles, all catalysts display similar activity (0.14–0.63 mol·gRu−1·h−1) and selectivity (≥99%) in the sunlight-powered Sabatier reaction. Ergo, the use of toxic and volatile Ru3(CO)12 can be avoided, since catalysts prepared by chemical reduction of RuCl3 display similar catalytic performance. [ABSTRACT FROM AUTHOR]

For effective CO2 methanation, monometallic Co(10)/SiO2 and Ni(10)/SiO2 and bimetallic Ni(5)Co(5)/SiO2 and Ni(2)Co(8)/SiO2 nanocomposite (NC) catalysts, where numbers between brackets indicate the metal content (wt%), have been prepared with solvate-stimulated modification, thermal decomposition, and chemical reduction stages using nanosilica A-300 as a carrier. The catalysts were characterized using SEM–EDX, nitrogen physisorption, and X-ray powder diffraction. The samples before and after the reduction with hydrogen have a similar mesoporous texture. The bimetallic Ni–Co/SiO2 NC catalysts showed improved catalytic activity compared to Ni/SiO2. The formers are characterized by the smallest bimetallic crystallites of ca. 12 nm in size. Activity in the methanation of the Ni–Co/SiO2 NC catalysts depends on the cobalt content resulting in a prominent increase in CO2 conversion and methane yield at 250–350 °C. The SEM–EDX analysis showed unusual flower-like nanostructures and proved the random distribution of Ni/Co bimetallic aggregates in the nanosilica matrix at the nanoscale level. Both Ni(2)Co(8)/SiO2 and Ni(5)Co(5)/SiO2 exhibited high activity in the CO2 methanation with 81–88% CH4 yield at 450 °C. The results of thermo-programmed desorption mass spectroscopy revealed that the catalytic reaction is passed through the formation of O-containing intermediates bound to the active Ni–Co and nanosilica sites. [ABSTRACT FROM AUTHOR]

[Display omitted] • OMNs Pt-Ru-Ir catalyst shows improved oxygen bifunctional electrocatalysis. • Superior ORR activity (0.21 mA/µg & 0.33 mA/cm2) with extended durability was found. • Excellent OER activity with low Tafel slope and enhanced durability obtained for Pt 70 Ru 25 Ir 5. • Synergistic and mesoporous morphology with trace Ir boosting the bifunctional oxygen kinetics. An efficient oxygen bifunctional catalyst Pt-Ru-Ir with ordered mesoporous nanostructures (OMNs) was successfully synthesized by chemical reduction using KIT-6 mesoporous silica as a template. The crystallographic behavior, electronic effects, and microstructure of the catalysts were investigated by XRD, XPS, SEM, and TEM analysis. The influence of OMNs and the effect of Ir content in Pt-Ru-Ir catalyst on both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) were investigated. The synergistic and electronic effects play an important role in electrocatalytic performance through the electronic coupling between Pt, Ru and Ir followed by the alloy formation with different lattice strain percentages. Amongst, the OMNs Pt 70 Ru 25 Ir 5 catalyst exhibits the highest mass activity of 0.21 mA µg−1 and specific activity of 0.33 mA cm−2 for ORR, which are nearly 5-fold greater than those for benchmark Pt/C catalyst. Furthermore, the Pt 70 Ru 25 Ir 5 demonstrated enhanced OER activity with an overpotential of 470 mV at 10 mA cm−2, an onset potential of 1.70 V, and a Tafel slope of 118 mV dec-1, outperforming commercial IrO 2. In addition, the durability of the Pt 70 Ru 25 Ir 5 catalyst for ORR and OER are found to be extended in comparison with that of other catalysts reported in this work after 6000 cycles. These results demonstrate that the ordered OMNs Pt-Ru-Ir with low Ir content (∼5 wt%) could be a promising oxygen bifunctional catalyst for electrochemical energy conversion and storage applications. [ABSTRACT FROM AUTHOR]

Photocatalytic CO2 reduction to valuable chemicals, especially fuels, is considered as a promising strategy to mitigate CO2 accumulation and tackle the energy crisis, among which photocatalysis is vital to achieve efficient and selective reduction of CO2. In this work, phosphorus-doped hollow polygonal g-C3N4 rods were prepared through phosphoric acid assisted self-assembly under hydrothermal conditions and subsequent thermal polymerization using phosphoric acid as the phosphorus source and melamine as the nitrogen-rich precursor. The resulting phosphorus-doped hollow polygonal g-C3N4 rods feature increased specific surface area, visible light absorption and photogenerated carrier separation and transfer efficiency according to the structure and photoelectric properties characterization. Coupled with an earth abundant metal-based complex, i.e. [Co(bpy)3]Cl2, as a co-catalyst, the phosphorus-doped hollow polygonal g-C3N4 rods deliver a CO evolution rate of up to 447.5 μmol g−1 h−1 with a selectivity of ca. 96%, being much higher compared to the pristine g-C3N4 (67.01 μmol g−1 h−1 with a selectivity of ca. 94%) resulting from the improved light harvesting and charge transfer to the co-catalyst. Remarkably, the phosphorus-doped hollow polygonal g-C3N4 rods can be reused 6 times while retaining constant catalytic activity in the photoreduction reaction. This work presents new insights into photocatalytic CO2 reduction by developing non-metal doping and hollow structural designs for semiconductor photocatalysts. [ABSTRACT FROM AUTHOR]

This work investigates the electrooxidation of glycerol in an alkaline environment at non‐doped and P‐doped Pt‐αNi(OH)2 nanoparticles supported on oxidized Vulcan XC‐72R carbon. Pt‐αNi(OH)2 and PtP‐αNi(OH)2 particles with sizes in the range of 3–5 nm were obtained via a one‐step chemical reduction approach. The physicochemical characteristics of the as‐prepared catalysts were studied by inductively coupled plasma‐optical emission spectrometry (ICP‐OES), energy dispersive X‐ray (EDX), X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and x‐ray diffraction (XRD) techniques. It was determined that the incorporation of phosphorus lead to the formation of amorphous PtP‐αNi(OH)2 deposits. TEM analysis showed that the incorporation of phosphorus into the bimetallic Pt‐αNi(OH)2 catalyst origins a remarkable reduction in the average size of the nanoparticles with a narrow size distribution. A substantial improvement in the electrocatalytic properties of the Pt‐αNi(OH)2 system toward the oxidation of glycerol was observed through P doping. The P‐doped electrocatalysts developed a mass current density of 60.3 mA mgPt−1 at 765 mV vs. RHE, which is about 5 and 45 times higher than those of commercial PtRu/C (12.3 mA mgPt−1) and as‐synthesized Pt‐αNi(OH)2/C (1.5 mA mgPt−1), respectively. The temperature‐dependent experiments displayed that the apparent activation energy for the reaction is halved upon the addition of phosphorus. [ABSTRACT FROM AUTHOR]

The synthesis of γ-valerolactone (GVL) from butyl levulinate (BL) hydrogenation over sulfonated activated carbon (SAC) supported SnRuB bifunctional catalysts was studied. These catalysts were characterized by ICP, nitrogen physisorption, XRD, HRTEM, XPS and NH3-TPD techniques. The SnRuB hydrogenation active site and surface acidic site of the SAC support are effectively retained by the co-impregnation followed by a chemical reduction process and display a prominent synergetic effect for BL hydrogenation to GVL. Under the optimal reaction conditions (180 °C, 3 MPa, 800 rpm, 3 h), BL conversion of 99.2% and GVL selectivity of 83.8% were obtained over the optimal 20Sn1RuB/SAC catalyst. The highest total fraction of the C＝O group, lattice oxygen (Oα) and oxygen vacancies (Oβ) and active SnOx species on the surface of the catalyst contribute to the best adsorption and hydrogenation ability for BL conversion to GVL over the 20Sn1RuB/SAC catalyst. The sulfonated carbon-supported SnRuB bifunctional catalyst also showed outstanding recyclability in six runs due to enhanced reduction degree of Snn+ species, and strong interaction between the SnRuB active site and SAC support. In sum, the sulfonated carbon-supported SnRuB bifunctional catalyst with low costs, high activity and good recyclability is a potential candidate for butyl levulinate hydrogenation to GVL. [ABSTRACT FROM AUTHOR]

Co–B has good catalytic activity in the hydrogenation reaction of unsaturated groups and has been widely studied and applied. Co–B catalysts were usually prepared by reducing cobalt salts with reducing agents. However, the high surface energy and magnetic properties of Co–B catalysts made the particles easily agglomerate. Then, agglomeration increased the particle size of the sample and reduced the effective surface area of the catalyst powder, which limited the catalytic activity of the Co–B catalysts. A new type of Co–B/copper nanowires/cetyl trimethyl ammonium bromide (Co–B/CuNWs/CTAB) catalyst with high catalytic activity was prepared by a chemical reduction in this work. The performance of Co–B/CuNWs/CTAB was studied in the hydrolysis of ammonia-borane (AB) and CuNWs inserted into the Co–B interlayer could avoid particle agglomeration, thereby effectively increasing the specific surface areas of the catalysts. Furthermore, the insertion of CuNWs facilitated the transportation of electrons and improved catalytic activity. The BET analysis shows that the maximum surface area of the sample is 148.9 m2/g. Meanwhile, the hydrogen generation rate of 13.46 L min−1·g−1 at 30 °C was obtained by using the synthesized Co–B/CuNWs/CTAB catalyst with a low activation energy of 8.771 kJ mol−1. [Display omitted] • Co–B/CuNWs/CTAB catalyst with high catalytic activity was prepared. • CuNWs inserted into the Co–B interlayer could avoid particle agglomeration. • CuNWs facilitated the transportation of electrons and improved catalytic activity. • CTAB controlled the morphology of catalyst. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction to value‐added chemicals/fuels provides a promising way to mitigate CO2 emission and alleviate energy shortage. CO2‐to‐CO conversion involves only two‐electron/proton transfer and thus is kinetically fast. Among the various developed CO2‐to‐CO reduction electrocatalysts, transition metal/N‐doped carbon (M‐N‐C) catalysts are attractive due to their low cost and high activity. In this work, recent progress on the development of M‐N‐C catalysts for electrochemical CO2‐to‐CO conversion is reviewed in detail. The regulation of the active sites in M‐N‐C catalysts and their related adjustable electrocatalytic CO2 reduction performance is discussed. A visual performance comparison of M‐N‐C catalysts for CO2 reduction reaction (CO2RR) reported over the recent years is given, which suggests that Ni and Fe‐N‐C catalysts are the most promising candidates for large‐scale reduction of CO2 to produce CO. Finally, outlooks and challenges are proposed for future research of CO2‐to‐CO conversion. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction to high-value-added chemicals is one of the most promising and challenging research in the energy conversion field. An efficient ECR catalyst based on a Cu-based conductive metal-organic framework (Cu-DBC) is dedicated to producing CH4 with superior activity and selectivity, showing a Faradaic efficiency of CH4 as high as ~80% and a large current density of −203 mA cm−2 at −0.9 V vs. RHE. The further investigation based on theoretical calculations and experimental results indicates the Cu-DBC with oxygen-coordinated Cu sites exhibits higher selectivity and activity over the other two crystalline ECR catalysts with nitrogen-coordinated Cu sites due to the lower energy barriers of Cu-O4 sites during ECR process. This work unravels the strong dependence of ECR selectivity on the Cu site coordination environment in crystalline porous catalysts, and provides a platform for constructing highly selective ECR catalysts. Crystalline porous catalysts with single Cu sites are dedicated to exploring the dependence of CO2 electroreduction selectivity on the coordination environment of catalytic sites. The conductive MOF Cu-DBC with oxygen-coordinated Cu sites shows a high Faradaic efficiency ~80% of CO2-to-CH4. [ABSTRACT FROM AUTHOR]

The purpose of this work is activity evaluation of optimized Pd–Cu/rGO as an anode catalyst for electrooxidation of low ethanol concentrations (5–50 mM) in order to use in fuel cell-based breath alcohol analyzer. Accordingly, a simple and one-step synthesis of Pd/rGO and Pd–Cu/rGO with an optimized Pd/Cu ratio was performed via the chemical reduction method and evaluated for ethanol oxidation reaction (EOR). According to the transmission electron microscopy (TEM) and cyclic voltammetry (CV), the particle size and electrochemical active surface area (ECSA) of Pd0.9–Cu0.1/rGO were 4.5 nm and 181.5 m2 g−1, respectively. The ratio of If/Ib was measured to be 0.7 and 2.6 for Pd/rGO and Pd0.9–Cu0.1/rGO in the 0.5 M KOH solution containing 50 mM ethanol, thus indicating that the presence of Cu in the alloyed catalyst structure improved the catalytic activity by removing carbonaceous intermediates from the catalyst surface. Obtained results revealed that the onset potential (Eonset) of Pd0.9–Cu0.1/rGO was negatively shifted to 240 mV, as compared to Pd/rGO and no carbonate blockage of Pd–Cu/rGO sites happened in the presence of K2CO3. Therefore, Pd0.9–Cu0.1/rGO could be regarded as a superior anode catalyst for use in the anion exchange membrane fuel cell-based breath alcohol analyzer. [ABSTRACT FROM AUTHOR]

In view of their unique characteristics and properties, silver nanomaterials (Ag NMs) have been used not only in the field of nanomedicine but also for diverse advanced catalytic technologies. In this comprehensive review, light is shed on general synthetic approaches encompassing chemical reduction, sonochemical, microwave, and thermal treatment among the preparative methods for the syntheses of Ag-based NMs and their catalytic applications. Additionally, some of the latest innovative approaches such as continuous flow integrated with MW and other benign approaches have been emphasized that ultimately pave the way for sustainability. Moreover, the potential applications of emerging Ag NMs, including sub nanomaterials and single atoms, in the field of liquid-phase catalysis, photocatalysis, and electrocatalysis as well as a positive role of Ag NMs in catalytic reactions are meticulously summarized. The scientific interest in the synthesis and applications of Ag NMs lies in the integrated benefits of their catalytic activity, selectivity, stability, and recovery. Therefore, the rise and journey of Ag NM-based catalysts will inspire a new generation of chemists to tailor and design robust catalysts that can effectively tackle major environmental challenges and help to replace noble metals in advanced catalytic applications. This overview concludes by providing future perspectives on the research into Ag NMs in the arena of electrocatalysis and photocatalysis. [ABSTRACT FROM AUTHOR]

• Adding Fe to magnetic Ni catalyst improved CO 2 methanation efficiency and selectivity. • Magnetic Ni 8 Fe 2 converted >80% of CO 2 to methane at a low temperature of 150 °C. • Optimal catalyst reduction temperature determined as 200 °C. The power-to-gas (PtG) method has significant potential as a strategy for storing excess renewable energy in the form of synthetic natural gas. PtG involves the hydrogenation of CO 2 to CH 4 from H 2 obtained from renewable energy. In this study, Ni–Fe catalysts with different Ni/Fe ratios were prepared for high-efficiency CO 2 methanation using chemical reduction with an external magnetic field. The Ni–Fe catalysts were characterized by XRD, inductively coupled plasma, and SEM-EDS measurements, and their performance and chemical properties were measured by H 2 temperature programmed reduction experiments. The catalyst with the best performance for CO 2 methanation had a ratio of Ni to Fe of 8/2 (Ni 8 Fe 2). The Ni 8 Fe 2 catalyst could convert over 80% of CO 2 to methane at 150 °C. In addition, the CH 4 selectivity of CO 2 methanation was 95% when the reaction conditions were controlled at H 2 /CO 2 = 4 and GHSV ∼1000 h−1. The low cost and simple preparation of these Ni–Fe catalysts have high potential for future commercialization. [Display omitted] [ABSTRACT FROM AUTHOR]

A low-cost Ni-B alloy catalyst was prepared by chemical reduction method and used for partial hydrogenation of fatty acid methyl esters. The conditions for catalyst preparation, including Ni to B ratio, pH of NaBH4 solution, types and quantity of metal modifiers were optimized. Ni-La-B, prepared by modification of Ni-B with La, showed significantly high catalytic partial hydrogenation activity. The optimum textural properties (small particle size, high specific surface area and well-defined pore structure) and electron enrichment of active Ni sites were the favorable factors for the high hydrogenation activity of Ni-La-B catalyst, which showed reasonable stability in catalyst recycle experiments. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel organbentonite-based Ni-B catalyst doped with the metal La has been obtained. • La doping inhibited the aggregation of the catalyst and has more active centers. • Use of ultrasound effectively accelerated the CTH process of FAMEs. • The kinetics and thermodynamics of the FAMEs hydrogenation have been researched. • The possible reaction mechanism of ultrasound-assisted CTH has been proposed. In this work, an efficient organobentonite-based Ni-La-B composite catalyst (Ni-La-B/OB) was synthesized through impregnation and chemical reduction method using cetyltrimethylammonium bromide (CTAB)-modified bentonite as support and along with the addition of the metal additive La, and then was employed as catalyst for the ultrasound-assisted catalytic transfer hydrogenation (CTH) reaction of fatty acid methyl esters (FAMEs). The characterization results suggested that the inclusion of La resulted in the generation of additional active site. Under the conditions of the mass ratio of solvent water, hydrogen donor isopropanol and FAMEs of 80:28:5 and the catalyst dosage of 10 wt.%, the conversion ratio of C18:2 (CR C182) reached 76.68 %, and the iodine value (IV) decreased from the initial value of 146.7 to 84.01. Kinetics and thermodynamics research showed that ultrasound-assisted CTH of FAMEs followed pseudo-first-order kinetics and was endothermic. Meanwhile, a possible reaction mechanism of the catalyst on CTH of FAMEs was proposed. The Ni-La-B/OB composite catalyst underwent four recirculated cycles, and no significant deactivation was observed. In addition, ultrasound-assisted CTH significantly improved the hydrogenation effect and shortened the reaction time in comparison with the conventional method. The Ni-La-B/OB composite was found to be an efficient hydrogenation catalyst for CTH, and the doping of La significantly enhanced the catalytic activity. [ABSTRACT FROM AUTHOR]

The production of tetrahydrofurfuryl alcohol (THFAL) from biomass-derived furfural (FF) via one-pot hydrogenation is challenging owing to the high hydrogen pressure and temperature requirements of the system. In this study, a hydrothermal method is used to synthesize a series of wrinkled silica (KCC-1) supports having different morphologies and textural properties by modulating the cetylpyridinium bromide hydrate (CPB)/tetraethyl orthosilicate (TEOS) ratio. Subsequently, Pd-supported KCC-1 catalysts are fabricated along with a Pd/SiO 2 catalyst (for comparative studies) via a chemical reduction method. Interestingly, the morphological features of the supports, such as the specific surface area, pore size, and Pd anchoring sites, differed significantly for different CPB/TEOS ratios. Among the synthesized catalysts, Pd/KCC 0.3, with the lowest proportion of Pd nanoparticles deposited on the external porous surface, exhibits the highest catalytic activity, owing to its large specific surface area and moderate pore size. Moreover, it shows the highest FF conversion of 100% and THFAL selectivity of 85% in 6 h at 50 °C under 20 bar H 2. • KCC-1 supports with different morphologies are prepared by tuning CPB/TEOS ratios. • The correlation between the morphological features and the catalytic activity of Pd-based catalysts have been investigated. • Pd/KCC-1 catalsyts show higher selectivity for one-pot hydrogenation of furfural compared to Pd/SiO 2. • Pd/KCC 0.3 catalyst with a large surface area and low fiber density showed the highest selectivity to THFAL. [ABSTRACT FROM AUTHOR]

The influence of the composition of the copper complex and the structure of the ligand on the selectivity of continuous hydrogenation processes of dicyclopentadiene and nitrobenzene, as well as the reductive alkylation of nitrobenzene with isobutanol, up to the production of various reduction products under the same conditions with a selectivity of up to 100%, was discovered. [Display omitted] The reaction of copper(II) acetate with furoic acids (2Hfur / 3Hfur) and imidazole (Im) in methanol resulted in mononuclear complexes [Cu(fur) 2 (Im) 2 (H 2 O)]·L (fur- = 2fur- (1 , 2), 3fur- (3); L = MeCN (1)) whose structures were determined by direct single crystal X-ray analysis. It was found for the first time that copper nanoparticles immobilized on the surface of γ-Al 2 O 3 obtained by chemical reduction of 1 , 2 and 3 (pre-deposited on the surface from solution) with sodium tetrahydroborate show high selectivity of mono- and dihydrogenation of tricyclo[5.2.1.02,6]deca-3,8-diene (dicyclopentadiene, DCPD). The catalytic activity tests show a high selectivity (97 %) of the catalyst obtained from an ethanolic solution of complex 1 in the reaction of partial hydrogenation to DHDCPD under continuous process conditions even at high conversion values (up to 96 %) and with an excess of hydrogen, whereas the catalyst obtained from an aqueous solution of complex 1 showed 98 % total hydrogenation product (THDCPD) selectivity. The catalysts based on all the complexes 1 – 3 were successfully used in reactions of nitrobenzene (NB) reduction to aniline (AN) and in the reductive alkylation of nitrobenzene with isobutanol (i -BAN) 100 % yields of aniline and N -isobutylaniline were obtained at LHSV 0.16 h−1. [ABSTRACT FROM AUTHOR]

• A value-added and efficient technology for recycling spent Ag-Al 2 O 3 catalyst is proposed. • High-value-added spherical silver powder is synthesized by a simple chemical reduction method. • A fitted mathematical model of particle size for silver powder is obtained. • The interactions between the factors are investigated. The spent Ag-Al 2 O 3 catalyst is an important silver secondary resource due to its high content of Ag. However, the most commonly used nitric acid leaching method produces toxic and harmful NO x gases. Herein, a novel clean method was proposed to treat the spent Ag-Al 2 O 3 catalyst using the green leaching agent cerium ammonium nitrate instead of nitric acid to effectively avoid the generation of toxic NO x gases. More importantly, value-added monodisperse micro-sized uniform spherical particles were synthesized directly from the leaching solution by a simple chemical reduction method. The influence of leaching conditions on the leaching ratio of Ag and leaching kinetics were discussed in detail. The response surface methodology was applied to optimize the synthesis parameters of silver powder and explore the interactions between the synthesis process parameters. Under the optimal leaching parameters, the leaching ratio of Ag reached 99.69 %. The leaching kinetic analysis of leaching indicated that the leaching reaction of spent Ag-Al 2 O 3 catalyst was controlled by chemical reaction. By the response surface methodology design, a fitted mathematical model of the particle size for silver powder and the optimum synthesis parameters of silver powder were obtained. The optimum synthesis parameters of silver powder were as follows: [Fe2+] = 1.08 mol/L, [Ag+] = 1.01 mol/L, and dispersant dosage of 2.05 wt%. The average experimental particle size of 1.337 μm was very close to the predicted value of 1.343 μm obtained from the fitted model, indicating that the fitted model of particle size for silver powders was very good. This process not only provides a clean and value-added method for recycling the spent Ag-Al 2 O 3 catalyst, but also helps to promote the balanced and high-value utilization of high-abundance cerium. [ABSTRACT FROM AUTHOR]

A simple method for the synthesis of pure-phase Ni 12 P 5 nanoparticles supported on N, P-doped carbon sheets was developed. The resulting Ni x P y @NPC 700 showed high catalytic activity towards toxic organic compounds reduction under both static and continuous flow condition. [Display omitted] • New method for synthesizing pure phase Ni 12 P 5 from nickel phosphine complex precursor was developed. • Ni x P y @NPC 700 possess porous structure, uniform nanoparticles, and unique surface acid sites. • Ni x P y @NPC 700 exhibited high catalytic activity towards 4-nitrophenol reduction under both static and continuous flow condition. • The catalytic mechanism were studied by controlled experiments and DFT calculations. The removal of toxic organic compounds from aqueous media through reduction reactions using nonnoble catalysts has attracted much attention in recent years. In this study, a simple method for the synthesis of pure-phase Ni 12 P 5 nanoparticles supported on N, P-codoped carbon (NPC) sheets was developed, in which a nickel phosphine complex was selected as the precursor due to its high Ni/P ratio, air stability and easy preparation. By controlling the pyrolysis temperature, Ni x P y @NPC 700 with a high dispersity and exposed active sites can be obtained, which was characterized by XRD, HRTEM, EDS, XPS, Raman and NH 3 -TPD. The catalytic performance of the composite in the reaction of 4-nitrophenol (4-NP) was assessed under mild conditions, exhibiting excellent catalytic activity with a low apparent activation energy E a (29.87 KJ·mol−1). In addition, the catalyst can be recycled without obvious loss of activity for up to ten successive cycles. The outstanding hydrogenation activity is ascribed to the exposed Ni 12 P 5 (3 1 2) crystal plane of Ni x P y @NPC 700 , which is attributed to the lower energy barrier required to form a hydrogen splitting state according to DFT calculations. Moreover, Ni x P y @NPC 700 was creatively coated in a Teflon tube with Nafion as the adhesive and constructed as a fixed-bed device. The continuous-flow catalytic reaction shows that the catalyst can maintain a satisfactory efficiency for approximately 6 h in the reduction of 4-NP and methyl orange (MO). These findings suggest that Ni x P y @NPC 700 is an ideal catalyst for industrial applications for the chemical reduction of toxic compounds from wastewater. [ABSTRACT FROM AUTHOR]

Constructing an efficient and reusable catalyst for catalyzing NaBH 4 hydrolysis for H 2 production is of vital significance. Herein, the Ru particles decorated Co 3 B-CoP heterostructures are obtained by chemical reduction and gas-phase phosphating treatment. The strong electronic interaction and abundant heterojunctions between the Co 3 B-CoP substrate and Ru particles have been elucidated. The optimal Ru 0.063 /Co 3 B-CoP catalyst exhibits a fast hydrogen generation rate (8875.8 mL min−1 g cat −1) and a high turnover frequency (636.0 min−1) at 25 °C, superior to most ever reported catalysts. The excellent NaBH 4 hydrolysis performance can be attributed to the lower activation energy (47.6 kJ mol−1) and the synergy between Co 3 B-CoP substrate and Ru particles. Density functional theory calculations show that electrons penetrate into Ru particles from Co 3 B-CoP substrate, in which the electron-rich Ru particles can selectively adsorb BH 4 − ions, while the electron-deficient Co 3 B-CoP facilitates the capture of H 2 O molecules, thereby synergistically promote the catalyzing NaBH 4 hydrolysis to produce H 2. [Display omitted] • Ru particles decorated Co 3 B-CoP are constructed by three controllable steps. • The heterostructure and electronic interaction of the catalyst have been confirmed. • The catalyst exhibits high HGR and TOF, superior to most ever reported catalysts. • The synergy between Ru and Co 3 B-CoP is the key reason for good performance. [ABSTRACT FROM AUTHOR]

Low working temperature and high sensitivity of gas sensors are critical in their practical applications; however, these properties are usually contradictory and cannot be realized simultaneously. Here, ZnO porous nanowires (PNWs) are prepared by a modified electrospinning method, and Pt nanoparticles (NPs) are doped on their surface by chemical reduction. The effects on morphology, specific surface area, and oxygen vacancy are discussed for the acetone gas-sensing performance. Results showed that Pt-ZnO PNWs responded optimally to acetone gas at 160 °C at 16.7–1.8 ppm, which was three-fold greater than that of pristine ZnO PNWs. In addition, the lowest detection limit is 50 ppb, a ten-fold lower level than pristine ZnO PNWs. The sensor exhibits superior acetone selectivity, humidity resistance, repeatability, long-time stability, noble metals, and a porous design with a large surface area, providing synergistic effects that increase the number of surface adsorption sites. Thus, the approach provided a new comprehension for loading a high-dispersibility catalyst onto the porous structure surface as a potential breath analyzer. [Display omitted] • Pt-ZnO with porous 1D nanowires morphology prepared by modified electrospinning. • The novel porous structure provided abundant active sites and diffusion channels. • Pt NPs doping induced more oxygen vacancy due to the catalytic action. • The Pt-ZnO PNWs sensor exhibited superior acetone sensing at low temperature. • The gas-sensing mechanism was expounded in detail. [ABSTRACT FROM AUTHOR]

The rapidly rising concentration of carbon dioxide (CO 2) in the atmosphere as a result of human activity poses serious threats and alarming situations not only to humans but also to our environment. Within the context of this agenda, electrochemical CO 2 reduction to value-added chemicals is one of the most effective approaches to lowering environmental CO 2 concentrations. However, this approach requires highly robust electrocatalysts; therefore, in the last few years, there has been a dramatic increase in the demand for the synthesis and development of efficient electrocatalysts. Recently, metal-organic framework (MOF)-based materials, having high porosity, large surface area, stability, and chemical tunability, have been extensively studied as an emerging class of electrocatalysts for CO 2 reduction reaction (CO 2 RR). In this article, we reviewed the fundamentals of CO 2 RR, including its mechanism and activity descriptors, and current developments in MOF-based electrocatalysts for CO 2 RR are described along with their underlying chemistry. Finally, we explore the current difficulties and potential future developments of MOFs for CO 2 RR. It is intended that this review will aid in the development of ever-more effective MOF-based materials for CO 2 abatement and raise awareness of the need for additional work to be done in order to explore MOFs' potential for tackling important environmental sustainability challenges. Particularly, ligand engineering in MOFs remains an important topic for developing a highly efficient CO 2 RR catalyst. [Display omitted] • Concepts of CO 2 RR, mechanisms, and MOFs fabrication strategies are highlighted. • Recent developments in MOFs-based materials as CO 2 RR electrocatalysts are reviewed. • The challenges and prospects with MOF-based materials for CO 2 RR are provided. [ABSTRACT FROM AUTHOR]