Jyoti V. Patil

The development of ternary metal oxide electrocatalysts with optimized electronic structures and surface morphologies has emerged as one of the effective strategies to improve the performance of electrochemical water splitting. In this work, ternary CoMoCe (CMC)-oxide electrocatalysts were successfully synthesized on nickel foam substrates via a hydrothermal technique and employed for their catalytic activity in an alkaline electrolyte. For comparison, binary counterparts (CoMo, CoCe, and MoCe) were also fabricated under similar conditions. The synthesized catalysts’ electrodes exhibited diverse surface architectures, including microporous-flake hybrids, ultrathin flakes, nanoneedle-assembled microspheres, and randomly oriented hexagonal structures. Among them, the ternary CoMoCe-oxide electrode exhibited outstanding bifunctional electrocatalytic activity, delivering low overpotentials of 124 mV for the hydrogen evolution reaction (HER) at −10 mA cm⁻², and 340 mV for the oxygen evolution reaction (OER) at 100 mA cm⁻², along with excellent durability. Furthermore, in full water-splitting configuration, the CMC||CMC and RuO₂||CMC electrolyzers required cell voltages of 1.69 V and 1.57 V, respectively, to reach a current density of 10 mA cm⁻². Remarkably, the CMC-based electrolyzer reached an industrially relevant current density of 1000 mA cm⁻² at a cell voltage of 2.18 V, maintaining excellent stability over 100 h of continuous operation. These findings underscore the impact of an optimized electronic structure and surface architecture on design strategies for high-performance ternary metal oxide electrocatalysts. Herein, a robust and straightforward approach is comprehensively presented for fabricating highly efficient ternary metal-oxide catalyst electrodes, offering significant potential for scalable water splitting.

In the present investigation, a one-step hydrothermal approach is proposed to synthesize Li⁺, Rb⁺, and In³⁺intercalated PW₁₂O₄₀ (PTA) thin films. The photoelectrochemical performance of the deposited Li₃PW₁₂O₄₀ (Li−PTA), Rb₃PW₁₂O₄₀ (Rb−PTA), and In₃PW₁₂O₄₀ (In−PTA) photocathodes were investigated using a two-electrode cell configuration of FTO/Li₃PW₁₂O₄₀/(0.1 M I⁻/I³⁻)_aq./Graphite. The energy band gaps of 2.24, 2.11, and 2.13 eV were observed for the Li−PTA, Rb−PTA, and In−PTA films, respectively, as a function of Li⁺, Rb⁺, and In³⁺. The evolution of the spinal cubic crystal structure with increased crystallite size was observed for Rb⁺ intercalation within the PTA Keggin structure, which was confirmed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) revealed a modification in the surface morphology from a rod-like structure to a densely packed, uniform, and interconnected microsphere to small and large-sized microspheres for Li−PTA, Rb−PTA, and In−PTA, respectively. Compositional studies confirmed that the composing elements of Li, Rb, In, P, W, and O ions are well in accordance with their arrangement for Li⁺, Rb⁺, In³⁺, P⁵⁺, W⁶⁺, and O²⁻ valence states. Furthermore, the J-V performance of the deposited photocathode shows power conversion efficiencies (PCE) of 1.25%, 3.03%, and 1.62%, as a function of the incorporation of Li⁺, Rb⁺, and In³⁺ ions. This work offers a one-step hydrothermal approach that is a prominent way to develop Li⁺, Rb⁺, and In³⁺ ions intercalated PTA, i.e., Li₃PW₁₂O_40, Rb₃PW₁₂O₄₀, and In₃PW₁₂O₄₀ photocathodes for competent solar energy harvesting.