Doped Nickel-Based Nanocatalysts for Electrochemical Water Splitting: A Review

The growing demand for clean energy solutions to address fossil fuel depletion and global warming has increased the pace for the search for sustainable alternatives. To address this situation, hydrogen energy is emerging as a promising method due to its zero pollution and high energy density. Electrocatalytic water splitting is a promising technology for large-scale hydrogen production. Generally, electrocatalysts work well for either the HER or the OER, but not both. Developing catalysts that can be efficiently used for overall water splitting is necessary for commercial viability. Nickel-based materials, specifically when doped with metals (e.g., Fe, Co, W, Cu, Ru, and Ir) and nonmetals (e.g., C, F, and P), have shown great potential because of their versatile chemical properties, corrosion resistance, and structural stability. This review provides a comprehensive overview of recent advancements in doped nickel-based electrocatalysts, which focuses on nickel oxides, chalcogenides, phosphides, nitrides, and single-atom catalysts (SACs). It discusses fundamental mechanisms of HER and OER, strategies for enhancing electrocatalytic performance through doping, defect engineering, and electronic structure modulation. It also discusses the effect of nonmetal and metal doping on activity and stability. The review also emphasizes the importance of systematic experimental approaches like doping ratios, accurate surface area corrections, and operando methods to better understand the relationship between electronic structure and electrocatalytic performance. It also highlights the research gaps and the future directions that aim to advance the design of efficient, stable, and cost-effective nickel-based electrocatalysts, which can contribute to the development of sustainable hydrogen energy production.