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The spent automobile catalysts (SAC) is the major secondary source of palladium and the production of SAC is increasing rapidly over years. The price of palladium keeps rising over the years, which demonstrates its preciousness and urgent industrial demand. Recovering palladium from the spent automobile catalysts benefits a lot from economic and environmental protection aspects. This review aims to provide some new considerations of recovering palladium from the spent automotive catalysts by summarizing and discussing both hydrometallurgical and pyrometallurgical methods. The processes of pretreatment, leaching/extraction, and separation/recovery of palladium from the spent catalysts are introduced, and related reaction mechanisms and process flows are given, especially detailed for hydrometallurgical methods. Hydrometallurgical methods such as chloride leaching with oxidants possess a high selectivity of palladium and low consumption of energy, and are cost-effective and flexible for different volume feeds compared with pyrometallurgical methods. The recovery ratios of palladium and other platinum-group metals should be the focus of competition since their prices have been rapidly increased over the years, and hence more efficient extractants with high selectivity of palladium even in the complexed leachate should be proposed in the future. [ABSTRACT FROM AUTHOR]

A novel CFCl2CF2Cl(R113)/H2 gas treatment process was proposed and successfully applied for the redispersion of a sintered alloy PdCu/AC catalyst. The redispersion process was initiated by the formation of an oxidative PdCuClx intermediate, which can easily migrate to a nearby catalyst surface and then be reduced to smaller PdCu NPs. [ABSTRACT FROM AUTHOR]

The article discusses research on gas-phase photocatalytic oxidation of benzene in a batch reactor using cerium zirconium oxide with surficial titanium dioxide. The chemistry of the process is explained and an optimal loading ratio of titanium dioxide is reported. Laboratory instrumentation used to characterize the photocatalyst included X-ray diffraction, UV-vis diffuse reflectance, and X-ray photoelectron spectroscopy. The researchers suggest that the photocatalytic oxidation mechanism involves electron transfer, increases in active surficial oxygen species, and the absorption spectrum of the catalyst.

• Co(NH 3) 6 3+ is better than Co(II) or Cu(II) in catalyzing gold thiosulfate leaching. • Co(NH 3) 6 3+ achieves faster gold leaching from the calcine than Co(II) and Cu(II). • Thiosulfate consumption caused by Co(NH 3) 6 3+ is lower than Co(II) and Cu(II). • Co(NH 3) 6 3+ makes gold recovery by resin adsorption more efficient than Co(II). Co(II) is effective in catalyzing gold thiosulfate leaching, but Co(III) has seldom been adopted directly as the catalyst. This paper examined the effect of hexaamminecobalt(III) on the thiosulfate leaching of gold from a concentrate calcine and the gold recovery via resin adsorption from the leach solution. Under the leaching solution conditions, the Co(NH 3) 6 3+/Co(NH 3) x 2+ (x = 4, 5) redox couple is thermodynamically formed playing the catalytic role. Experimental results verify the catalysis of Co(NH 3) 6 3+, which is better than that of Co(II) and Cu(II) in thiosulfate leaching of gold. Replacing Cu(II) by Co(NH 3) 6 3+ or Co(II), the thiosulfate consumption was significantly reduced and the complex two-stage gold elution process was simplified to a low-cost one-stage process. Compared with Co(II), Co(NH 3) 6 3+ that is already the oxidant could shorten the leaching time from 8 h to 6 h without affecting the gold extraction (~80%). In addition, the thiosulfate consumption was further lowered from 18.8 kg·t-1 ore to 15.0 kg·t-1 ore under the catalysis of Co(NH 3) 6 3+, which was confirmed by the X-ray photoelectron spectroscopy (XPS) analysis. Based on the thermodynamic analysis, the decrease of thiosulfate consumption may result from the formation of a lower concentration of the mixed-ligand Co(III) complexes such as Co(NH 3) x (S 2 O 3)+ (x = 4, 5). Gold recovery results suggested that, comparing Co(NH 3) 6 3+ with Co(II), the gold in the Co(NH 3) 6 3+ catalyzed leaching solution could be recovered more efficiently by resin adsorption. Therefore, Co(NH 3) 6 3+ is a catalyst more efficient than Co(II) and has promise to replace Cu(II) in the extraction and recovery of gold from its ores by thiosulfate leaching and resin adsorption. [ABSTRACT FROM AUTHOR]

Abstract: The present work focuses on the electrocatalytic effect of nano-SiO2 on nickel electrodeposition and chemical interaction between nano-SiO2 and nickel in composite coating. The electrochemical behavior from n-SiO2/Ni composite brush plating system and quick nickel solution are investigated using cyclic voltammetry. The interaction between n-SiO2 particles and matrix metal nickel is researched by X-ray photoelectron spectrometry. The results show that the n-SiO2 take part in the electrode reaction during nickel electrocrystallization and can catalyze the nickel electrodeposition. The unsaturated bond of oxygen on n-SiO2 particles surface can capture some of the absorbed nickel atoms and form nickel–oxygen chemical bond. It is proved that the chemical binding interaction exists in the interface between nanoparticles surface and matrix metal nickel. [Copyright &y& Elsevier]

Focuses on the application of surface interaction of supported catalysts in industrial reactions. Findings of investigations conducted; Details and information on catalysts; Factors which influence the application of catalysts.

[Display omitted] Platinum group metal (PGM)-free catalysts represented by nitrogen and iron co-doped carbon (Fe-N-C) catalysts are desirable and critical for metal-air batteries, but challenges still exist in performance and stability. Here, cerium oxides (CeO x) are incorporated into a two-dimensional Fe-N-C catalyst (FeNC-Ce-950) via a host-guest strategy. The Ce4+/Ce3+ redox system creates a large number of oxygen vacancies for rapid O 2 adsorption to accelerate the kinetics of oxygen reduction reaction (ORR). Consequently, the as-synthesized FeNC-Ce-950 catalyst exhibits a half-wave potential (E 1/2) of 0.921 V and negligible decay (<2 mV for Δ E 1/2) after 5,000 accelerated durability cycles, significantly outperforming most of ORR catalysts reported in recent years and precious metal counterparts. When applied in a zinc-air battery, it demonstrates a peak power density of 175 mW cm−2 and a specific capacity of 757 mAh g Zn −1. This study also provides a reference for the exploration of Fe-N-C catalysts decorated with variable valence metal oxides. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mo-based MXene is first applied as a cathode catalyst for Li-CO 2 batteries. • An innovative surface modification strategy, mild oxidation by CO 2 , is employed. • The catalyst optimizes the growth and decomposition of discharge products. • This MoO 2 @Mo 2 C-based Li-CO 2 battery outperforms most other MXene-based catalysts. The lithium-carbon dioxide (Li-CO 2) batteries hold promise for energy storage, given their capacity to capture and convert carbon dioxide (CO 2). However, the practical application of Li-CO 2 batteries continues to face substantial obstacles caused by sluggish CO 2 reduction/evolution kinetics, resulting in high overpotential and short lifespan. This work presents the fabrication of a highly effective MoO 2 @Mo 2 C heterostructure hybrid catalyst using a CO 2 oxidation strategy. This strategy integrated (in-situ) MoO 2 onto the surface of two-dimensional (2D) Mo 2 C MXene, enhancing catalytic activity while preserving 2D electron/ion pathways. As a result, the MoO 2 @Mo 2 C, when used as a catalyst in Li-CO 2 battery showcased a discharge capacity of 20790.8 mAh g−1 at a current density of 200 mA g−1. Notably, it achieved a long cycling life of 230 cycles at a cutoff capacity of 1000 mAh g−1 with a voltage gap as low as 1.85 V, which was significantly superior to that of a pristine Mo 2 CT x catalyst (3.61 V after twenty cycles). This work provides critical insights into the design of MXenes-based high-performance catalysts for advanced Li-CO 2 batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Iohexol degradation in Fe 3 O 4 /O 3 system was higher than in O 3 only system. • Trace HBT could enhance iohexol degradation efficiency in Fe 3 O 4 /O 3 system. • 1O 2 and radicals of O H ∙ , and O 2 - ∙ were identified in the Fe 3 O 4 /O 3 /HBT system. • Iohexol degradation mechanisms and pathways in the Fe 3 O 4 /O 3 /HBT system were proposed. This study explored the degradation of an iodine X-ray contrast media, iohexol, under heterogeneous ozone-catalyzed oxidation by adding Fe 3 O 4 and 1-hydroxybenzotriazole (HBT). Results show that increasing the dosages of Fe 3 O 4 catalyst and ozone as well as solution pH were beneficial to the degradation of iohexol. The presence of low background humic acid (HA) concentration (≤10 mg/L) promoted iohexol degradation, but high HA concentration (≥20 mg/L) inhibited it. Adding HBT exhibited a similar effect on iohexol degradation as HA. The degradation rate constant of iohexol was calculated as 0.07108 min−1 in the Fe 3 O 4 /O 3 /HBT process ([HBT] = 5 μM) at pH 7.0, which was approximately 1.5 times higher than that in the Fe 3 O 4 /O 3 process (0.04533 min−1), and 4 times higher than that in the O 3 process (0.01742 min−1). Fe 3 O 4 /O 3 /HBT process was pH-dependent with high degradation efficiency of iohexol at pH 5 or 7. Singlet oxygen (1O 2), hydroxyl radical (OH ∙), and superoxide radical (O 2 - ∙) have been identified in the Fe 3 O 4 /O 3 /HBT process, and the conversion of Fe2+ to Fe3+ was more obvious on the surface of Fe 3 O 4 compared to that in the Fe 3 O 4 /O 3 process. Transformation intermediates were identified, and the degradation pathways of iohexol were proposed. Overall, Fe 3 O 4 /O 3 could enhance iohexol degradation compared with ozone-only system, and adding trace HBT in Fe 3 O 4 /O 3 system can further enhance heterogeneous ozone-catalyzed process for rapid organic matter degradation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stable encapsulated SC@MoS 2 crystal was facilely fabricated by hydrothermal method. • MoS 2 coating facilitated electron transfer and rapidly activated PMS to generate reactive oxygen species. • Oxygen defects and transition metals act as active sites for the activation of PMS. • Feasibility of SC@MoS 2 /PMS system was proved by organic pollutants degradation and reusability. Perovskite oxides and molybdenum sulfide (MoS 2) are both promising catalysts for advanced oxidation processes in environmental pollutant degradation. Herein, a core-shell structure of MoS 2 encapsulating Sr-Co perovskite microcrystalline (SC@MoS 2) was used to activate peroxymonosulfate (PMS) for degradation of organics. Levofloxacin (LVF) degradation by SC@MoS 2 /PMS system was improved obviously, and 0.2-SC@MoS 2 exhibited the optimized activation for PMS with best LVF degradation performance (97%) within 15 min. In the 0.2-SC@MoS 2 /PMS system, the dosage of catalyst was the key determinant of LVF degradation. Simultaneously, 0.2-SC@MoS 2 achieved outstanding reusability and good degradation capacity of different contaminants. The encapsulation of molybdenum disulfide layer facilitated electron transfer between PMS and core-shell structure. According to the EPR analysis and quenching experiments, both radicals (SO 4 − and OH), and nonradical (1O 2) were involved in the degradation of LVF. Under visible light irradiation, O 2 − participated in the reaction and enhanced LVF degradation efficiency, because the valence band and conduction band of components are different. Furthermore, the density functional theory (DFT) calculation, intermediates determination and Toxicity Estimation Software Tool (T.E.S.T) analysis provided meaningful support in the degradation pathways and ecological risks of LVF residues. [ABSTRACT FROM AUTHOR]

ORR: oxygen reduction reaction; SMSI: strong metal-support interaction; LABI: Lewis acid-base interaction. [Display omitted] • Residual Zn in various ZIF-8 derived carbons could reach ∼10 wt%. • ZnN x could act as 'spatial barriers' suppressing Pt forming ORR inactive PtN x. • ZnN x could serve as Zn source for the intermetallation of L1 0 -PtZn. • ZnN x could bring the SMSI between PtZn and support. • LABI between ZnN x and PtCl 6 2− could promote the dispersion of PtZn. ZIF-8 derived carbons demonstrate admirable application prospects in electrocatalytic fields, while ZnN x remaining in those materials are overlooked, crippling the validity of theoretic studies in researches. Herein, the residual Zn in ZIF-8 derived carbons are found could exceed 10 wt% even at carbonization temperatures over 900℃, and Zn-NCs with various Zn contents are adopted as supports to synthesize low-platinum ORR catalysts. Substantial characterizations manifest that ZnN x in Zn-NC can not only provide Zn source for L1 0 -PtZn intermetallic, but act as 'spatial barriers' to prevent the formation of inactive PtN x , elevating the active Pt proportion in catalyst by ∼104%. The resultant Zn-NC-Ar-PtZn exhibits a mass activity of 0.557 mA/g Pt and a peak density of 1.485 W/cm2. DFT calculations show the strong thermodynamic tendency of forming PtN 4 without the protection of ZnN 4 , and the superior durability and activity of Zn-NC-Ar-PtZn should be attributed to its Zn-derived ligand effects and the SMSI. [ABSTRACT FROM AUTHOR]

Abstract We report the preparation of an ammonia borane hydrolysis catalyst for use in hydrogen production by dispersing Rh nanoparticles on a nitrogen-doped carbon (NPC) support. The resulting Rh/NPC catalyst had a measured turnover frequency of 473.5 min−1, higher than that of many previously reported Rh-based catalysts. This catalyst could also be reused eight times. The large surface area and abundant nitrogen-functional species of NPCs facilitate dispersion of Rh nanoparticles on their surface, providing numerous catalytically active sites for ammonia borane hydrolysis, thereby leading to high catalytic activity. This study demonstrates that NPC support can be used to prepare highly active catalysts. Highlights • Well dispersed Rh nanoparticles with clean surfaces on NPC were prepared. • Rh/NPC exhibited high activity and reusability for ammonia borane hydrolysis. • A high turnover frequency of 473.5 min−1 was obtained under optimum conditions. [ABSTRACT FROM AUTHOR]

Fe-Mn oxides was prepared by thermal activation of Mn-rich limonite at different temperatures, and then developed as catalysts for low-temperature NH 3 -SCR. The obtained samples were characterized by XRD, XRF, TEM, XPS, BET, H 2 -TPR, NH 3 -TPD, NH 3 -SCR model reaction and in situ DRIFTS. The results indicated that Fe-Mn oxides catalyst derived from the thermal treatment at 300 °C (H300) exhibited an excellent NO conversion which was higher than 90% at a temperature range from 130 to 300 °C. The large surface area (95.9 m 2 /g), large amount of acid sites, suitable reduction behavior, and abundant surface hydroxyl positively responsed to the excellent performance of H300 for NH 3 -SCR. The results of in situ DRIFTS and kinetic study demonstrated that when the SCR reaction temperature reached to 100 °C, both the Eley–Rideal mechanism and the Langmuir-Hinshelwood mechanism might happen over H300. However, the Langmuir-Hinshelwood mechanism could be approximately neglected at higher reaction temperatures. This study favors the understanding of NH 3 -SCR mechanism of the prepared provides Fe-Mn oxides and explores new application field for Mn-rich limonite in low-temperature NH 3 -SCR. [ABSTRACT FROM AUTHOR]

Developing effective catalysts for hydrogen evolution from hydrolysis of ammonia borane (AB) is of great significance considering the useful applications of hydrogen. Herein, graphitic carbon nitride (g-C 3 N 4 ) prepared through the simply pyrolysis of urea was employed as a support for Rh nanoparticles (NPs) stabilization. The in-situ generated Rh NPs supported on g-C 3 N 4 with an average size of 3.1 nm were investigated as catalysts for hydrogen generation from the hydrolysis of AB under mild conditions. The Rh/g-C 3 N 4 catalyst exhibits a high turnover frequency of 969 mol H 2 · (min·mol Rh ) −1 and a low activation energy of 24.2 kJ/mol. The results of the kinetic studies show that the catalytic hydrolysis of AB over the Rh/g-C 3 N 4 catalyst is a zero-order reaction with the AB concentration and a first-order reaction with the Rh concentration. This work demonstrates that g-C 3 N 4 is a useful support to design and synthesis of effective Rh-based catalyst for hydrogen-based applications. [ABSTRACT FROM AUTHOR]

The heterogeneous photo-Fenton technology by integrating the merits of photocatalysis and Fenton oxidation is verified to be a promising environmental purification technology due to its relatively mild reaction conditions, low cost and high treatment efficiency. Herein, we demonstrate the fabrication of Type-II CuCo 2 S 4 /Bi 2 WO 6 heterojunction as an effective catalyst for the removal of tetracycline hydrochloride (TC-HCl). Two photoactive components are combined to form a two-dimensional/two-dimensional (2D/2D) heterojunction by coupling 2D CuCo 2 S 4 with 2D Bi 2 WO 6 nanosheets, in which CuCo 2 S 4 cocatalyst broadens the light responsive range, facilitates the separation and transfer of photogenerated carriers. Most importantly, CuCo 2 S 4 initiates the photo-Fenton catalysis by utilization photogenerated electrons to react with Cu (II) and Co (III) in presence of hydrogen peroxide (H 2 O 2) to accelerate the circulation of the photo-Fenton reaction. Thus, the generated OH and·O 2 - are applied as potent free radical species for the catalytic degradation of pollutants. The synthesized CuCo 2 S 4 /Bi 2 WO 6 heterostructures exhibited excellent photo-Fenton catalytic activity for TC-HCl removal. The rate constant (k app /min−1) of 0.5% CuCo 2 S 4 /Bi 2 WO 6 heterojunction is about 1.8 times higher than pure Bi 2 WO 6. Recycling experiments show that the catalyst maintained its high activity after being reused for 4 cycles, reflecting its good stability. Meanwhile, hydroxyl radical (·OH) and superoxide radical (·O 2 -) were identified as oxygen active species, taking a key role in the degradation of TC-HCl. Based on the trapping experiment and energy band analysis, a reasonable photo-Fenton oxidation mechanism for Type-II CuCo 2 S 4 /Bi 2 WO 6 heterojunctions is put forward. This work will arouse researchers' enthusiasm for introducing transition metal sulfides as cocatalyst to design heterogeneous photo- Fenton catalyst. In-situ coupling two-dimensional (2D) CuCo 2 S 4 nanosheets on 2D Bi 2 WO 6 nanosheets to efficiently facilitate the separation and transfer of photogenerated charges for photo-Fenton degradation of TC-HCl. [Display omitted] • CuCo 2 S 4 /Bi 2 WO 6 heterojunctions were synthesized by in-situ hydrothermal reaction. • The unique 2D/2D heterojunction can efficiently facilitate the separation and transfer of photogenerated charges. • The synthesized CuCo 2 S 4 /Bi 2 WO 6 heterojunctions exhibited excellent photo-Fenton catalytic activity for the degradation of TC-HCl. • A reasonable photo-Fenton oxidation mechanism for Type-II CuCo 2 S 4 /Bi 2 WO 6 heterojunctions is proposed. [ABSTRACT FROM AUTHOR]

In situ hydrogenation of unsaturated compounds by released hydrogen from various hydrogen sources is a good strategy to achieve highly selective hydrogenation. In this work, inexpensive CuO/TiO 2 nanocomposites were systematically screened their performance for catalyzing dehydrogenation of ammonia borane (AB) and the tandem hydrogenation of some nitroaromatics. Those CuO/TiO 2 binary nanocomposites were found to maximize the hydrogen production from the catalytic hydrolysis of AB. Owing to a positive in-situ hydrogen activation, under mild conditions these CuO/TiO 2 nanocomposites exhibited highly excellent reactivities accompanying with better recyclability in the current one-pot hydrogenation. Notably, a selected CuO (0.5) /TiO 2(0.5) nanocomposites displayed high activity and regioselectivity (up to100% yield of aim product) as well as increased ability of inhibiting the dehalogenation reaction, especially for 4-bromonitrobenzene or 4-iodonitrobenzene (up to 71.65% yield for 4-bromoaniline or 68.02% yield of 4-iodoaniline). Moreover, that CuO (0.5) /TiO 2(0.5) nanocomposites from a co-precipitation method displayed relatively better recyclability against those two control samples obtained from a stepwise preparation process. Owing to positive in-situ hydrogen activation mechanism, CuO/TiO 2 binary nanocomposites from co-precipitation method display highly excellent reactivity, regioselectivity, and better recyclability for the tandem hydrogenation of aromatic nitro-compounds under highly mild conditions. [Display omitted] • Binary CuO/TiO2 nanocomposites exhibited attractive reactivity toward the tandem hydrogenation of nitro-compounds. • Control experiments powerfully confirm a positive in-situ hydrogen activation benefitting the efficient tandem hydrogenation. • Distinguishable catalytic performances were observed for those catalysts coming from different preparation methods. [ABSTRACT FROM AUTHOR]

Abstract: Two model spherical iron catalysts (100Fe/0Al2O3 and 100Fe/15Al2O3) with free Cu and K promoters were prepared by the combination of co-precipitation and spray drying method for the application of slurry Fischer–Tropsch synthesis (FTS). The effect of Fe–Al2O3 interaction on the reduction/carburization behavior in H2/CO/syngas, surface basicity and the change of phase structure were comparatively studied by means of H2 or CO temperature-programmed reduction (TPR), CO2 temperature-programmed desorption (TPD) and Mössbauer effect spectroscopy (MES). The results showed that the catalyst incorporated with Al2O3 exhibits a strong Fe–Al2O3 interaction, which obviously weakens the surface basicity, stabilizes the FeO phase and inhibits the reduction of iron catalyst in H2 or syngas. Furthermore, Fe–Al2O3 interaction also restrains the carburization of iron catalyst in CO or syngas. In slurry FTS process, it was found that the strong Fe–Al2O3 interaction decreases the FTS activity and suppresses the water gas shift (WGS) reaction, but can stabilize the active sites of iron catalyst and improve its run stability. Due to the strong Fe–Al2O3 interaction, the weak surface basicity on the catalyst incorporated with Al2O3 greatly decreases the selectivity of heavy hydrocarbon products. [Copyright &y& Elsevier]

Abstract: An industrial iron-based catalyst (100Fe/5Cu/6K/16SiO2, by weight) was characterized after reduction at different temperatures and after Fischer–Tropsch synthesis (FTS) in a stirred tank slurry reactor (STSR). The BET surface area and pore volume of the catalyst decreases with increasing reduction temperature, and the contrary trend was found for pore size. The iron phase compositions of catalysts reduced with syngas were strongly dependent on pretreatment conditions employed. Pretreatment with syngas at lower temperature prevents iron catalyst activation. Carburization was intensified with the increase in reduction temperature. The formation of iron carbides in reduced catalyst was necessary for obtaining stable high FTS activity. The relationship between the amount of CO2 in tail gas during activation and the Fe3+ (spm) content in the reduced catalyst was observed. The rapid carburization at high reduction temperature resulted in the formation of a superparamagnetic Fe3+ core and an iron carbide layer of the reduced catalyst. FTS activity decreased with the increase in the reduction temperature, but the stability distinctly improved. It was found that the working catalyst loss in the heavier waxy products resulted in higher deactivation rate of the catalyst reduced at lower temperature. With the increase in the reduction temperature, the product distribution shifted towards the lower molecular weight products. [Copyright &y& Elsevier]

It was shown by transmission electron microscopy (TEM) that there contain nanoscale crystalline inclusions about several nanometers in dimension in diamond single crystals synthesized in the presence of Fe70Ni30 alloy catalyst under high pressure and high temperature (HPHT). The inclusions distribute homogeneously within the diamond matrix. It was indicated by selected area electron diffraction (SAD) patterns combined with EDS analyses that the inclusions consist of three main types: hexagonal graphite with a lattice constant of a=2.463 A˚, c=6.714 A˚, f.c.c. (FeNi)23C6 with a lattice constant of a=10.89 A˚, and f.c.c. γ-(FeNi) with a lattice constant of a=7.146 A˚. [Copyright &y& Elsevier]

Highly efficient and durable anode electrocatalysts are the key to boost the performance of direct organic-molecule fuel cells (DOMFCs), yet there are still many challenges need to be solved. The PdPt alloy nanocrystals have been regarded as the most promising anode catalysts of DOMFCs, and the further improvement of their catalytic performance has attracted much attention. The effective routes includes tailoring the surface structure and optimizing the alloy composition of PdPt nanocatalysts. The high-index faceted structures possess high density of terraces and atomic steps which are efficient for electrooxidation reactions of small organic-molecule fuels, such as formic acid and ethanol. In particular, electrochemically-controlled synthesis methods present unique advantages in achieving such high-index faceted nanostructures. The current paper reports a direct electrodeposition of PdPt concave nanocubes on carbon paper (denoted as PdPt-CNC/CP). The prepared PdPt-CNC/CP has high-index faceted surface structures varying from {610} to {830}. When served as electrocatalysts, the PdPt-CNC/CP brings in outstanding mass specific activity and durability towards both formic acid oxidation reaction (FAOR) and ethanol oxidation reaction (EOR). More importantly, the selectivity of complete oxidation pathway through the cleavage of C-C bond on PdPt-CNC/CP during EOR in alkaline solution has been confirmed through NMR analysis. Based on the convenient method of direct electrodeposition of PdPt concave nanocubes on carbon paper and their excellent catalytic activity and durability, the PdPt-CNC/CP catalysts have potential advantages in being used as catalyst layers directly for membrane electrode assembly (MEA) in fuel cells, due to the reduced catalyst loading and simplified assembly process in comparison with traditional preparation procedure. Image 1 [ABSTRACT FROM AUTHOR]

• Synergy between Ni(OH) 2 and MoS x (MoS x : amorphous molybdenum sulfide) catalysts promotes alkaline HER performance. • Electrodeposition of Ni(OH) 2 and MoS x inspires facile approach for catalyst synthesis. • Oxidized carbon fiber provides hydrophilic substrate in favor of uniform electrodeposition in aqueous media. The efficient electrochemical hydrogen evolution reaction in alkaline media through the use of earth-abundant catalysts has received significant attention, as it is a crucial means for sustainable H 2 production. Here, we present a facile synthesis approach for Ni(OH) 2 /MoS x (MoS x : amorphous molybdenum sulfide) catalyst on oxidized carbon fiber support. Carbon fibers are first oxidized by a hydrothermal treatment in a concentrated HNO 3 solution, while Ni(OH) 2 and MoS x films are consecutively deposited onto the substrate through simple electro-deposition methods from their plating solutions. Benefiting from the hydrophilicity of the oxidized carbon fiber, the abundant electrochemically reactive sites and the synergistic effect between Ni(OH) 2 and MoS x , this hybrid catalyst shows a low HER onset potential of 80 mV at 1 mA/cm2, an overpotential of 180 mV at 10 mA/cm2 and a remarkable stability of at least 35 working hours at a H 2 -evolving current density of 10 mA/cm2 without any obvious overpotential changes. [ABSTRACT FROM AUTHOR]