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The rational design of high-efficiency electrocatalysts for application in water oxidation in alkaline media remains a great challenge. In this paper, Ni3+-rich nanograss-like Mo-doped Ni3S2/NiS/VS arrays grown on nickel foam (denoted as Mo-NiVS@NF) have been successfully constructed through a hydro/solvothermal method. Interestingly, Mo-NiVS@NF exhibits superior catalytic OER performance, needing an overpotential of 217 mV to drive a current density of 10 mA cm−2, outperforming most previously reported NiS-based electrocatalysts. The result indicates that the Ni3+-rich active sites caused by the modulation of the electronic structure environment via the introduction of V and high-valency Mo play an important role in the high activity for the OER. Moreover, this catalyst shows high long-term electrochemical durability. [ABSTRACT FROM AUTHOR]

The electrocatalytic urea oxidation reaction (UOR) has attracted substantial research interests over the past few years owing to its critical role in coupled electrochemical systems for energy conversion, for example, coupling with the hydrogen evolution reaction (HER) to realize urea-assisted hydrogen production and assembling direct urea fuel cells (DUFC) by coupling with the oxygen reduction reaction (ORR). The UOR process has been proved to be a two-step process which involves an electrochemical pre-oxidation reaction of the metal sites and a subsequent chemical oxidation of the urea molecules on the as-formed high-valence metal sites. Hence, designing advanced (pre-)catalysts with a boosted pre-oxidation reaction is of great importance in improving the UOR performance and thus accelerating the coupled reactions. In this feature article, we discuss the significant role of the pre-oxidation process during the urea electro-oxidation reaction, and summarize detailed strategies and recent advances in promoting the pre-oxidation reaction, including the modulation of the crystallinity, active phase engineering, defect engineering, elemental incorporation and constructing hierarchical nanostructures. We anticipate that this feature article will offer helpful guidance for the design and optimization of advanced (pre-)catalysts for UOR and related energy conversion applications. [ABSTRACT FROM AUTHOR]

The increasing energy demand and related environmental issues have drawn great attention worldwide, thus necessitating the development of sustainable technologies to preserve the ecosystems for future generations. Electrocatalysts for energy-conversion reactions such as the hydrogen evolution reaction (HER), nitrogen reduction reaction (NRR), and carbon dioxide reduction reaction (CO2RR) are at the heart of these renewable energy technologies, but they suffer from sluggish kinetics due to the multistep electron and mass transfer. State-of-the-art catalysts are thus highly desired to boost the conversion efficiencies, which are still inadequate. Recently, as a typical transition metal dichalcogenide, molybdenum disulfide (MoS2) with unique physicochemical properties has been verified as a promising material for catalyzing key electrochemical reactions (i.e., HER, NRR, and CO2RR), presenting excellent performances. Therefore, in this review, we give insight into the structure and synthetic strategies of MoS2. Recent advances in MoS2-based materials for the three key electrochemical reactions are briefly summarized. Open challenges and perspectives of MoS2-based electrocatalysts toward HER, NRR, and CO2RR are also outlined. [ABSTRACT FROM AUTHOR]

This work presents a highly active electrocatalyst of CO2-derived hierarchical carbon. It retains a high surface area and enables homogeneous insertion of Fe–N–C active sites for the oxygen reduction reaction. The electrocatalyst with a highly interconnected porous structure provides oxygen reduction reaction activity with an E1/2 difference of 10 mV and a high current density equivalent to Pt/C 20 wt%. [ABSTRACT FROM AUTHOR]

NiCl2·6H2O ([Ni(H2O)6]2Cl2) per se does not show electrocatalytic hydrogen evolution reaction activity (HER) in an acidic aqueous medium as well as in neutral water. Interestingly, when [Ni(H2O)6]2+ is present in a polyoxovanadate matrix, for example, in the compound K2[Ni(H2O)6]2[V10O28]·4H2O (1), it exhibits homogeneous electrocatalytic HER activity in an acidic aqueous solution with a turn over frequency of 2.1 s−1 and an effective low overpotential of 127 mV at pH 2.3. Compound 1 is the first nickel-containing polyoxometalate catalyst for hydrogen production via homogeneous electrocatalytic proton reduction without its decomposition under electrochemical conditions of HER. [ABSTRACT FROM AUTHOR]

Hybrid Ni3S2–MoS2 NWAs/NF, hybrid Ni3S2–MoS2 nanowire arrays in situ grown on Ni foam via a two-step hydrothermal method, can achieve cathodic current densities of 10 mA cm−2 and 100 mA cm−2 at overpotentials of 99 mV and 260 mV in 1.0 M KOH and 111 mV and 194 mV in 0.5 M H2SO4, respectively. It still needs an overpotential of 103 mV at 10 mA cm−2 in 0.1 M PBS. This work opens a new avenue for designing heterogeneous active electrocatalysts for energy conversion and storage. [ABSTRACT FROM AUTHOR]

Ru, RuO2 and MoO3 embedded carbon nanorods (Ru–RuO2/MoO3 CNRs) were synthesized through electrospinning and low-temperature calcination. Results of comprehensive characterizations suggest that the strong interaction between Ru and Mo species, large electrochemical surface area, and high electrical conductivity (a proper ratio of RuO2 to Ru) endow Ru–RuO2/MoO3 CNRs-350 with excellent hydrogen evolution reaction (HER) performance. [ABSTRACT FROM AUTHOR]

We demonstrate a lamellar NiMoCo@CuS catalyst, showing not only an excellent catalyst performance (η100@72 mV and a Tafel slope of 47 mV dec−1), but also a good stability (20 mA cm−2@30 hours), outperforming the NiMo system and noble Pt. [ABSTRACT FROM AUTHOR]