Tapping the Potential of High-Valent Mo and W Metal Centers for Dynamic Electronic Structures in Multimetallic FeVO(OH)/Ni(OH) for Ultrastable and Efficient Overall Water Splitting.

Rationally designing a noble metal-free electrocatalyst for OER and HER is pivotal for large-scale energy generation via water splitting. A multimetallic electrocatalyst FeVO(OH)/NiMoW(OH), aimed at tuning the electronic structure, is fabricated and shows considerable improvement in the water-splitting reaction kinetics, aided by low Tafel slope values of 24 mV/dec for OER and 67 mV/dec for HER, respectively. By taking advantage of (e̅-e̅) repulsions at the t level, we introduced high-valency Mo and W to provide a viable path for π-electron donation from oxygen 2p orbitals to vacant Mo and W orbitals for a dynamic electronic structure and an interfacial synergistic effect, which optimized the bond lengths for reaction intermediates to facilitate water splitting.

Diffusion-Mediated Morphological Transformation in Bifunctional MnO/CuO-(VO)(PO)·6HO for Enhanced Electrochemical Water Splitting.

A strategical approach for morphological transformation and heterojunction formation was utilized to suppress the shortcomings of uni-metal oxide electrocatalysts and enhance their bifunctionality. In situ generation of copper oxide (CuO) over the surface of manganese oxide (MnO) resulted in a morphological transformation from solid spheres to hollow spherical structures due to the ion-exchange diffusion (Kirkendall effect) of Cu ions into MnO particles. This hollowness resulted in the advancement of the bifunctional electrocatalytic behavior of MnO/CuO (overpotential (η) of 280 mV for an OER and 310 mV for an HER at a current density of 10 mA/cm) by virtue of increased exposed surface active sites aiding the adsorption of water molecules on the surface.

Hierarchical FeO(OH)-CoCeV (Oxy)hydroxide as a Water Cleavage Promoter.

The search for a bifunctional electrocatalyst having water cleavage promoting ability along with the operational stability to efficiently generate oxygen and hydrogen could lead to robust systems for applications. These fundamental ideas can be achieved by designing the morphology, tuning the electronic structure, and using dopants in their higher oxidation states. Herein, we have fabricated a binder-free FeO(OH)-CoCeV-layered triple hydroxide (LTH) bifunctional catalyst by a two-step hydrothermal method, in which the nanograin-shaped FeO(OH) coupled with CoCeV-LTH nanoflakes provides more electrocatalytically active sites and enhances the charge-transfer kinetics for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER).

A Z-Scheme Strategy that Utilizes ZnIn S and Hierarchical VS Microflowers with Improved Charge-Carrier Dynamics for Superior Photoelectrochemical Water Oxidation.

One of the major limiting factors for efficient photoelectrochemical water oxidation is the fast recombination kinetics of photogenerated charge carriers. Herein, we propose a model system that utilizes ZnIn S and hierarchical VS microflowers for efficient charge separation through a Z-scheme pathway, without the need for an electron mediator. An impressive 18-fold increase in photocurrent was observed for ZnIn S -VS compared to ZnIn S alone.