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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]

[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 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]

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 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]

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]

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]

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]

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]

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]

[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]

[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]

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 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]

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]

An aqueous colloidal dispersion of Pt nanoparticles (NPs) stabilized by fullerenol C60(OH)12 (Pt:C60(OH)12) was successfully synthesized via liquid‐phase chemical reduction. The subsequent pyrolysis of Pt:C60(OH)12 at different temperatures was conducted to afford Pt‐doped carbon with different chemical compositions (Pt:C60n). X‐ray absorption spectroscopy (XAS) and Infrared (IR) absorption spectroscopy and thermogravimetric measurements revealed that the thus‐prepared nanocomposite consists of Pt NPs and high valent Pt‐C60(OH)12 complex. One distinct feature of C60(OH)12 matrix as catalyst support is the suppression of size growth of Pt NPs during the pyrolysis up to 300 °C. Electrochemical experiments using cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were performed to find that Pt:C60300 (pyrolyzed at 300 °C) exhibited higher activity than others, that was attributed to the π‐extended feature of the as‐obtained carbon. [ABSTRACT FROM AUTHOR]

In this study, the high activity Ni – Li – B catalysts were fabricated through wet chemical reduction method. Their morphological structures, crystallinity, surface area and composition were examined by field-emission scanning electron microscopy (FE - SEM), X-ray diffraction (XRD), Brunauer – Emmett – Teller (BET) method and energy-dispersive X-ray spectroscopy (EDS). The aluminum-water reaction tests were explored in the range of temperatures from 35 – 75 °C. It was found that water could react with aluminum to generate hydrogen gas. The yield and hydrogen generation rate were significantly increased when all prepared catalysts were added into the reaction. The Ni – Li – B (X LiCl = 0.1 g) catalyst exhibited the highest cumulative hydrogen volume of 201.3 ml with an average hydrogen production rate of 0.50 ml min − 1 at 55 °C. This phenomenon could be pointed to the emergence of the micro galvanic cell formed by the Ni – Li – B, Li/Ni – Li – B, Li and Al, which accelerated aluminum to rapidly react with water. • High activity Ni–Li–B catalyst was synthesized via wet chemical reduction method. • Ni–Li–B catalyst greatly enhances the aluminum-water reaction. • The hydrogen generation rate promoted by Ni–Li–B (LiCl = 0.1 g) is improved significantly. • The Ni–Li–B catalysts are inexpensive and are easily prepared by wet chemical reduction method. [ABSTRACT FROM AUTHOR]

In this study, fumed silica (FS), reduced graphene oxide (rGO), and their hybrid (FS-rGO) are tested as support materials for Au nanoparticles to prepare anode catalysts for sorbitol fuel cells. Chemical reduction method is used to obtain Au@FS, Au@rGO, and Au@FS-rGO catalysts characterized by SEM, EDAX, TEM, XRD, and Raman analysis. The Au contents of the catalysts are determined as 32.5% (Au@FS), 32% (Au@rGO), and 32.8% (Au@FS-rGO). Diameters of Au nanoparticles are measured as 1.51 nm (Au@FS), 5.90 nm (Au@rGO), and 7.05 nm (Au@FS-rGO). The highest current density for sorbitol oxidation is obtained with Au@FS-rGO. The onset potential of sorbitol oxidation obtained with Au@FS-rGO (0.007 V) is much smaller than those of Au@FS (0.028 V) and Au@rGO (0.038 V), indicating the synergistic effect of FS and rGO. FS significantly increases the activity and stability of the catalysts compared to rGO one of the commonly researched support materials in fuel cells. [Display omitted] • FS, rGO and FS-rGO hybrid were tested as catalyst supports for sorbitol fuel cells. • Au nanoparticles were formed on FS, rGO, or FS-rGO hybrid to obtain catalysts. • Activities of the catalysts in sorbitol oxidation were measured in KOH solution. • FS-rGO hybrid showed the highest activity in sorbitol oxidation as a support. • Nanocomposite of FS and Au showed exceptional stability in sorbitol oxidation. [ABSTRACT FROM AUTHOR]

The electrodeposition of tin and tin-nickel on a highly dispersed carbon material is used to obtain composite supports. These composite supports were used in the Pt(0) nanoparticles deposition from Pt(IV) solution by chemical reduction. The composition, structure, and activity of the obtained Pt(SnO2/C) and PtSnNi/C catalysts in the oxygen reduction and alcohol electrooxidation reactions were studied. The composite-support-based platinum catalysts exhibit higher activity in the reactions of alcohols electrooxidation in comparison with the commercial Pt/C analogue. Trimetallic PtSnNi/C catalysts are the most promising materials for the electrooxidation of alcohols. [ABSTRACT FROM AUTHOR]

Summary The development of highly active and cost effective catalysts for hydrolysis of sodium borohydride (NaBH4) is the main aim for practical usage of NaBH4 for fuel cells. Herein, we investigated the addition of various amounts of Triton during chemical reduction process on the NiB catalytic activity. The experimental results indicated that the catalytic performance of Triton stabilized NiB catalysts was significantly higher than that of NiB catalysts. Furthermore, the highest hydrogen generation rate in NaBH4 hydrolysis was obtained with 25 μL Triton addition as 8970 mL.min−1.g−1cat at 338 K. The activation energy of the hydrolysis for NiB25 and NiB catalysts were calculated as 48.05 and 58.91 kJ mol−1, respectively. In the second part of this study, the kinetic performance of NaBH4 hydrolysis was experimentally studied, and subsequently generated hydrogen from the hydrolysis reaction was fed directly to the fuel cell and the performance analysis were investigated. It was found that the power density of pure hydrogen was lower than the hydrogen generated by the NiB25 catalysts. Our results clearly indicated that Triton possessed a significant effect on the catalytic activity of NiB catalyst. [ABSTRACT FROM AUTHOR]

• Ni@Pd/C and Ni@PdRh/C core–shell nanoparticles were synthesized. • Catalytic activity toward ethanol oxidation depends on structure and composition. • The addition of Rh improves the catalytic activity and stability of Ni@Pd/C. • Ni@PdRh/C exhibited the highest catalytic activity for ethanol electro-oxidation. • The catalytic activity for Ni@PdRh/C was three times higher, compared to Pd/C. This paper describes the synthesis and catalytic activity of carbon-supported Pd/C, PdNi/C, and PdNiRh/C catalysts with core–shell morphologies towards the oxidation of ethanol in alkaline media. The catalysts are synthesised by a chemical reduction method using sodium borohydride as the reducing agent. Electrochemical characterisations show that the addition of Ni and Rh enhances remarkably the electrocatalytic activity of the materials due to the bifunctional and electronic effects in PdNi/C and PdNiRh/C catalysts, and the synergetic effect of the bifunctional and core–shell morphology on the Ni@Pd/C and Ni@PdRh/C catalysts. Electrochemical impedance spectra reveal lower values of charge transfer resistance for Pd 60 Ni 20 Rh 20 /C and Ni 20 @Pd 60 Rh 20 /C. Chronoamperometric tests also reveal the Ni 20 @Pd 60 Rh 20 /C catalyst displays current densities 9.3 times higher than the Pd/C catalyst. The superior catalytic performance of the trimetallic core–shell Ni 20 @Pd 60 Rh 20 /C catalyst can result from the synergy between the metals and the presence of core–shell morphology. [ABSTRACT FROM AUTHOR]

Ru-Fe bimetallic alloy nanoparticle catalyst (Ru-Fe/GO) was prepared by chemical reduction method on graphene oxide prepared using Hummers modified method. The structure and morphology of both GO and Ru-Fe/GO were analyzed using X-ray diffraction (XRD), Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS).The effect of catalyst components on hydrogen generation rate for NaBH4 methanolysis was investigated. When Ru:Fe is 6:1, the catalytic activity is the highest, and the average rate is about 473 mL·min−1·g−1. The effect of temperature, Sodium hydroxide concentration, and sodium borohydride concentration on reaction rate is also discussed, and the activation energy for the methanolysis of sodium borohydride is 59.33 kJ·mol−1 based on the data. [ABSTRACT FROM AUTHOR]

Research in the development of new molecular catalysts for the selective transformation of CO2 to reduced forms of carbon is attracting enormous interest from chemists. Molecular catalyst design hinges on the elaboration of ligand scaffolds to manipulate the electronic and structural properties for the fine tuning of the reactivity pattern. A cornucopia of ligand sets have been designed along this line and more and more are being reported. In this quest, the porphyrin molecular platform has been under intensive focus due to the unmatched catalytic properties of metalloporphyrins. There have been rapid advances in this particular field during the last few years wherein both electronic and structural aspects in the second coordination spheres have been addressed to shift the overpotential and improve the catalytic rates and product selectivity. Metalloporphyrins have also attracted much attention in terms of the elaboration of hybrid materials for heterogeneous catalysis. Here too, some promising activities have made metalloporphyrin derivatives serious candidates for technological implementation. This review collects the recent advances centred around the chemistry of metalloporphyrins for the reduction of CO2. [ABSTRACT FROM AUTHOR]

Co-Mo particles were loaded on three dimensional graphene oxide (3DGO) carrier via a chemical reduction method to get a composite catalyst, Co-Mo/3DGO, for hydrogen generation from NaBH 4 hydrolysis. Hydrolysis measurement shows that the ratio Co:Mo = 0.7:0.3 realizes a much higher hydrogen generation rate (HGR) of 7023.3 mL H 2 ⋅ min − 1 ⋅ g M − 1 , about 1.6 times of that for the Mo element undoped Co/3DGO (4394 m L H 2 . min − 1. g M − 1 ) catalyst. And the reaction activation energy is as low as 35.6 kJ mol − 1. The as prepared Co 0.7 Mo 0.3 /3DGO catalyst disperses on 3DGO surface as smaller particles than Co/3DGO, and presents a waxberry like structure with more active sites for catalysis reaction, which enables the catalyst a superior catalytic activity. Besides abundant active sites, MoO 3 supported active blend of Co and CoO is another reason for the higher activity. Image 1 • Co-Mo/3DGO, catalyst for NaBH 4 hydrolysis was prepared. • The Co-Mo/3DGO catalyst presented a waxberry like structure with more active sites. • The catalyst had a superior catalytic activity, and HGR was 7023.3 mL H 2 ⋅ min − 1 ⋅ g M − 1 [ABSTRACT FROM AUTHOR]

High-throughput (HT) methodology was applied for the synthesis, characterization and catalytic testing of Cu- and Ni-based catalysts for glucose hydrogenation. Design of Experiment (DoE) was used in all steps. The deposition and reduction of both metals was performed using chemical reduction with hydrazine method. In total 36 catalysts were synthetized, characterized and tested in 5 days. The amount of metal deposited on the support was chosen as the discriminative and determining parameter. The catalysts were tested at low temperature in the hydrogenation of glucose to sorbitol. • High-throughput methods allow shortening the time of development of a new catalytic process. • Ni and Cu-supported catalysts can be easily obtained by reduction-precipitation method. • The activity strongly depends on preparation conditions. • The use of Design of Experiments (DoE) permits to minimize the number of experiments and to optimize their interpretation. • Good performances in hydrogenation of glucose to sorbitol were obtained for Cu/SiO 2 and Ni/Al 2 O 3 catalysts. A high-throughput (HT) methodology was applied for the synthesis, characterization and catalytic testing of silica and alumina supported Cu- and Ni-based catalysts for glucose hydrogenation. A design of Experiment (DoE) approach was also used in all steps. The deposition and reduction of both metals was performed using the chemical reduction with hydrazine method. In total, 36 catalysts were synthetized, characterized and tested in 5 days. The amount of metal deposited on the support was chosen as the discriminative and determining parameter. The catalysts were tested at low temperature (130 °C) in the hydrogenation of glucose to sorbitol. The results showed that the chemical reduction-precipitation method could be performed using fully automatized robots. The deposition of the metals strongly depended on the nature of the support, the temperature of the reduction and hydrazine/H 2 O ratio. The maximum metal precipitation occurred at higher temperature (70 °C) and lower N 2 H 4 /H 2 O ratio (0.04 mol/mol) in both cases. The results clearly showed that glucose conversion is higher for the catalysts synthesized at 70 °C compared to the catalysts synthesized at 50 °C, irrespective of the metal precursors, supports and hydrazine/water ratios employed during catalysts syntheses. With a total timespan of around 5 days we showed that HT methods applied to all the steps (synthesis, characterization and testing) can significantly reduce the time needed to develop a new catalytic process. [ABSTRACT FROM AUTHOR]

Al-water reaction promoted by catalysts is a promising hydrogen generation technology. In this work, a high-activity M-B/γ-Al 2 O 3 (M = Co, Ni) catalyst is prepared by wet chemical reduction method. It is found that M-B/γ-Al 2 O 3 catalyst significantly promotes the Al-water reaction and decreases the induction time. When the molar ratio of γ-Al 2 O 3 to Co-M in Co–B/γ-Al 2 O 3 catalyst is 1:1, the induction time is only 0.43 h. The catalytic activity of M-B/γ-Al 2 O 3 is proportional to its active area. SEM analyses show that M-B particles are dispersed on γ-Al 2 O 3 surface, which reduces the agglomeration of M-B and increases the active surface of M-B/γ-Al 2 O 3 , leading to a high catalytic activity. A possible mechanism is proposed, which shows that the dissociation of water molecules on γ-Al 2 O 3 surface and the microgalvanic interaction between M-B and Al can promote the hydration process of passive oxide film on Al particle surface, speeding up the Al-water reaction. Image 1 • High-activity M-B/γ-Al 2 O 3 catalyst was prepared by wet chemical reduction method. • M-B/γ-Al 2 O 3 greatly promotes the Al-water reaction and decreases the induction time. • The catalytic activity of M-B/γ-Al 2 O 3 is proportional to its active area. • A possible mechanism for Al-water reaction promoted by M-B/γ-Al 2 O 3 was proposed. [ABSTRACT FROM AUTHOR]

Understanding photodriven multielectron reaction pathways requires the identification and spectroscopic characterization of intermediates and their excited‐state dynamics, which is very challenging due to their short lifetimes. To the best of our knowledge, this manuscript reports for the first time on in situ spectroelectrochemistry as an alternative approach to study the excited‐state properties of reactive intermediates of photocatalytic cycles. UV/Vis, resonance‐Raman, and transient‐absorption spectroscopy have been employed to characterize the catalytically competent intermediate [(tbbpy)2RuII(tpphz)RhICp*] of [(tbbpy)2Ru(tpphz)Rh(Cp*)Cl]Cl(PF6)2 (Ru(tpphz)RhCp*), a photocatalyst for the hydrogenation of nicotinamide (NAD‐analogue) and proton reduction, generated by electrochemical and chemical reduction. Electronic transitions shifting electron density from the activated catalytic center to the bridging tpphz ligand significantly reduce the catalytic activity upon visible‐light irradiation. [ABSTRACT FROM AUTHOR]