Fabrication and Characterization of Controlled-Morphology Self-Supported Fe/Co Layered Double Hydroxides as Catalysts for the Oxygen Evolution Reaction

Research on engineered electrocatalysts for efficient water splitting: a comprehensive review

Water electrolysis plays an interesting role toward hydrogen generation for overcoming global environmental crisis and solving the energy storage problem. However, there is still a deficiency of efficient electrocatalysts to overcome sluggish kinetics for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Great efforts have been employed to produce potential catalysts with low overpotential, rapid kinetics, and excellent stability for HER and OER. At present, hydrogen economy is driven by electrocatalysts with excellent characteristics; thus, systematic design strategy has become the driving force to exploit earth-abundant transition metal-based electrocatalysts toward H₂ economy. In this review, the recent progress on newer materials including metals, alloys, and transition metal oxides (manganese oxides, cobalt oxides, nickel oxides, PBA-derived metal oxides, and metal complexes) as photocatalysts/electrocatalysts has been overviewed together with some methodologies for efficient water splitting. Metal-organic framework (MOF)-based electrocatalysts have been highly exploited owing to their interesting functionalities. The photovoltaic-electrocatalytic (PV-EC) process focused on harvesting high solar-to-hydrogen efficiency (STH) among various solar energy conversion as well as storage systems. Electrocatalysts/photocatalysts with high efficiency have become an urgent need for overall water splitting. Also, cutting-edge achievements in the fabrication of electrocatalysts along with theoretical consideration have been discussed.

Earth-Abundant Electrocatalysts for Water Splitting: Current and Future Directions

Of all the available resources given to mankind, the sunlight is perhaps the most abundant renewable energy resource, providing more than enough energy on earth to satisfy all the needs of humanity for several hundred years. Therefore, it is transient and sporadic that poses issues with how the energy can be harvested and processed when the sun does not shine. Scientists assume that electro/photoelectrochemical devices used for water splitting into hydrogen and oxygen may have one solution to solve this hindrance. Water electrolysis-generated hydrogen is an optimal energy carrier to store these forms of energy on scalable levels because the energy density is high, and no air pollution or toxic gas is released into the environment after combustion. However, in order to adopt these devices for readily use, they have to be low-cost for manufacturing and operation. It is thus crucial to develop electrocatalysts for water splitting based on low-cost and land-rich elements. In this review, I will summarize current advances in the synthesis of low-cost earth-abundant electrocatalysts for overall water splitting, with a particular focus on how to be linked with photoelectrocatalytic water splitting devices. The major obstacles that persist in designing these devices. The potential future developments in the production of efficient electrocatalysts for water electrolysis are also described.