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To achieve sustainable production of H 2 fuel through water splitting, noble-metal-free catalysts have been extensively studied for hydrogen evolution reaction (HER), especially molybdenum-based catalysts. Herein, we report the Ni, N-codoped MoC x (Ni–N–MoC x ) nanoparticles synthesized from NiMoO 4 precursor by oily-solvent-assisted strategy, following the calcination with dicyandiamide. As-obtained Ni–N–MoC x in different magnified SEM images shows grainy structure, MoC x nanoparticles uniformly disperse in carbon substrate. The obtained electrocatalysts can also efficiently electrocatalytic HER in a wide pH value. Ni–N–MoC x shows an onset potential of −74 mV, an overpotential of 163 mV to reach a current density of 10 mA/cm 2 in acid media, an onset potential of −37 mV and overpotential of 124 mV to reach 10 mA/cm 2 in alkaline media. The present study provides some guidelines for preparing the uniformly doped electrocatalysts from multiple compounds with devolatilization characteristics. [ABSTRACT FROM AUTHOR]

Cobalt nanoparticles encapsulated in nitrogen-doped carbon nanotubes (Co@N C) are obtained by a simple pyrolysis of Co-MOF (ZIF-67) for the bifunctional water recovery and hydrogen production. The results showed that calcination temperature of ZIF-67 significantly affected the morphology and catalytic performance. Wastewater are effectively recovered in the presence of the Co@N C and oxidant, which is promoted by anodic oxidation reactions. Co@N C as the cathode catalyst exhibited excellent hydrogen evolution reaction catalytic activity with a low onset potential of −51 mV (vs. RHE, current density of 0.5 mA/cm 2 ), Tafel slope of 96.73 mV/dec and extraordinary long-term durability. Finally, as a proof of concept, a home-made two-electrode device employed Co@N C as both anode and cathode catalyst for continuous water recovery and simultaneous hydrogen production, which possesses the possibly applications in solving the environmental pollution and energy crisis. [ABSTRACT FROM AUTHOR]

The development of photoelectrodes capable of light-driven hydrogen evolution from water with non-noble metals is an important approach for the storage of solar energy in the form of a chemical energy carrier. In this study, we report Co nanoparticles@N-doped carbon coated on carbon nanotube@defective-silica (CNTs@Co@NC/D-SiO 2 ), which are composed of Co nanoparticles@N-doped carbon as electrocatalyst, defective-silica as photocatalyst and carbon nanotube as conductive substrates. The obtained non-noble photocathode possesses the high performance for efficient photoelectrochemical hydrogen evolution reaction. When evaluated for hydrogen evolution reaction electrocatalysis, CNTs@Co@NC/D-SiO 2 exhibits a small onset overpotential of 104 mV (J = 1 mA cm −2 ), a Tafel slope of 69.1 mV dec −1 and outstanding long-term cycling stability. The P type semiconductor characteristics of CNTs@Co@NC/D-SiO 2 due to defective-silica with carrier concentration of 3.53 × 10 19 cm −3 is measured, which produces a significant positive shift of overpotential of 40 mV (J = 10 mA cm −2 ) under 100 mW cm −2 simulated sunlight irradiation. These findings provide a straightforward and effective route to produce cheap and efficient photo-electro-catalyst for water splitting. [ABSTRACT FROM AUTHOR]

A facile method was demonstrated for the preparation of Pt 3 Ni alloy nanoparticles supported on a sandwich-like graphene sheets/carbon nanospheres/graphene sheets substrate (Pt 3 Ni–C/rGO) through a one-pot solvothermal process in N,N-dimethylformide without the addition of reducing agents and surfactants. Transmission electron microscopic measurements showed that carbon nanospheres were homogeneously dispersed in the matrix of exfoliated graphene sheets, and Pt 3 Ni nanoparticles were distributed on the graphene surfaces without apparent agglomeration, where the average core size was estimated to be 12.6 ± 2.4 nm. X-ray photoelectron spectroscopic studies demonstrated that electron transfer likely occurred from the Pt 3 Ni alloy nanoparticles to the graphene sheets. Electrochemical measurements showed that the mass activity of the Pt 3 Ni–C/rGO catalysts in methanol oxidation was 1.7-times higher than that of Pt 3 Ni nanoparticles supported on reduced graphene oxide alone (Pt 3 Ni/rGO), and 1.3-times higher than that of commercial Pt/C (20 wt%). Additionally, CO tolerance and durability were also remarkably enhanced. These superior electrocatalytic activities were attributed to the following major factors: (i) the insertion of carbon nanospheres into the graphene matrix prevented restacking/refolding of the graphene sheets, leading to an increasing number of accessible active sites as well as transport channels for mass and charges; and (ii) the synergetic effect between Pt 3 Ni nanoparticles and rGO weakened the bonding interactions with reactant species, as manifested by the enhanced kinetics of methanol oxidation and CO oxidative desorption. [ABSTRACT FROM AUTHOR]