Synergistic influence of multivalent Ruδ+ on a CeOx nanocatalyst for self-powered efficient electrochemical water splitting

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2025-01, Vol.13 (1), p.368-386
• Main Authors: Mondal, Papri, Baitalik, Sujoy
• Format: Article
• Language: English
• Subjects: Charge density; Electric potential; Electrocatalysts; Electrochemistry; Electron states; Energy conversion; Energy conversion efficiency; Fabrication; Flux density; Hydrogen evolution reactions; Metal air batteries; Nanocomposites; Oxygen evolution reactions; Portable equipment; Splitting; Valency; Voltage; Water splitting; Zinc-oxygen batteries
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d4ta04989f

In spite of the rapid development of portable water-splitting devices based on rechargeable metal–air batteries, there is a scarcity of efficient multifunctional electrocatalysts (ECs) for oxygen reduction, oxygen evolution, and hydrogen evolution reactions (ORR/OER/HER). Herein, a multicomponent–multivalent coupling strategy involving surface-interface engineering is adopted for the development of an efficient trifunctional (TF) EC through the integration of dominant CeOx (CO) with a small fraction of Ru0 (R0) and RuOx (RO). Under tuned metal valency-composition, the designed multi-interfacial CO/R0/RO nanocomposite (NComp) shows enhanced ORR (E1/2 of 0.936 V), OER [overpotential (η10) of 166 mV at 10 mA cm−2], and HER (η10 of 58 mV) activity. Moreover, the drastically enhanced activity of CO/R0/RO is achieved with a small cell voltage of as low as 1.49 V, required to accomplish overall water splitting (OWS) at 10 mA cm−2. In addition, a large peak power density of 376.4 mW cm−2 and a low charge–discharge voltage gap of 0.247 V are observed for zinc–air batteries (ZABs) with admirable cycling stability (over 2000 h/12 000 cycles). In addition to ZABs, CO/R0/RO NComp is employed to mimic the functionality of Li–air batteries (LABs). For practical utility, an integrated device consisting of a symmetric two-electrode water splitting electrolyzer powered by two series-connected ZABs is realized using CO/R/RO as a single catalyst, which efficiently drives OWS and effectively produces H2 and O2 with production rates of 399.3 and 199.6 μL min−1, respectively. Moreover, the observed high faradaic efficiencies of 98.9% for the HER and 98.4% for the OER illustrate the effective energy conversion and high efficiency of this self-powered system. Thus, this work presents a feasible strategy of surface engineering via alteration of surface electronic states and concurrent fabrication of value-added highly efficient TF ECs, paving the way for their widespread adoption in energy-related devices.