Construction of Ni3+-rich nanograss arrays for boosting alkaline water oxidation

NiFe codoping-regulated amorphous/crystalline heterostructured Co-based hydroxides/tungstate with rich oxygen vacancies for efficient water oxidation catalysis

Oxygen evolution reaction (OER) is a crucial half-reaction in water splitting, generating hydrogen for sustainable development, but it is often subject to sluggish kinetics. Abundant transition metal-based OER electrocatalysts have been utilized to expedite the process. However, traditional amorphous catalysts suffer from low conductivity, while the activity of crystalline catalysts is also unsatisfactory. Herein, an amorphous/crystalline heterostructured Co-based hydroxide/tungstate was meticulously constructed and further tailored using a NiFe codoping method (NiFeCoW). Following NiFe codoping, the electronic structure had been modulated, subsequently altering the adsorption toward intermediates. From the electrochemical measurements, the NiFeCoW catalyst demonstrated superior electrocatalytic activity for OER in alkaline media, with a minimal overpotential of 297 mV at 10 mA cm-2 and a cell voltage of 1.57 V for water splitting. This study provides valuable guidance for regulating the amorphous/crystalline heterophase in catalysts through bimetallic modulating engineering.

Structurally engineered highly efficient electrocatalytic performance of 3-dimensional Mo/Ni chalcogenides for boosting overall water splitting performance

Hydrogen production from water splitting combined with renewable electricity can provide a viable solution to the energy crisis. A novel MoS2/NiS2/Ni3S4 heterostructure is designed as a bifunctional electrocatalyst by facile hydrothermal method to demonstrate excellent electrocatalytic performance towards overall water splitting applications. MoS2/NiS2/Ni3S4 heterostructure necessitates a low overpotential of 81 mV and 210 mV to attain a current density of 10 mA cm-2 during the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Consequently, the MoS2/NiS2/Ni3S4 heterostructure-based electrolyzer shows a low cell voltage of 1.54 V at 10 mA cm-2. The present work highlights the significance of the heterostructure configuration of transition metal sulfide-based electrocatalysts for electrochemical overall water splitting applications.

Branched Porous Ni3N as a Catalytic Electrode for Selective Semidehydrogenation of Tetrahydroisoquinoline

Oxygen evolution in electrochemical water splitting needs a high overpotential that significantly reduces the energy efficiency. To explore an alternative anodic reaction to promote the production of hydrogen at the other end of water splitting and at the same time to get high-value-added chemicals is highly desirable. Herein, we demonstrate a novel branched porous Ni3N catalyst that is prepared for dehydrogenation of tetrahydroisoquinoline, which acts as an anodic oxidation reaction to promote H2 formation on the other end. Interestingly, the Ni3N catalytic electrode can induce effective semidehydrogenation with the selective formation of dihydroisoquinoline, which is difficult to be obtained by the usual direct synthesis route. The catalytic electrode exhibits a low potential of 1.55 V (vs RHE) for a catalytic current density of 61 mA cm-2 with dehydrogenation of tetrahydroisoquinoline and hydrogen production. In situ Raman spectra studies suggest that NiOOH is formed on the electrode surface, which mediates the oxidation semidehydrogenation process. This work also provides a strategy to fabricate nitride materials for applications beyond selective semidehydrogenation of tetrahydroisoquinoline.

Insights into Fe-doping effect-induced heterostructure formation for the oxygen evolution reaction

Fe-doping effect-induced heterostructure formation and charge redistribution in Fe-doped NiS were revealed significantly for boosting the electrochemical oxygen evolution reaction.