DFT-Driven Approaches to Optimizing Small Bandgap Doping Structures: A Brief Review

Photoelectrochemical (PEC) efficiency, is crucial for absorbing sunlight to initiate water splitting for hydrogen generation, is influenced by material’s structure. Small bandgap metal oxides (SBGMO) with bandgaps < 2.8 eV are promising candidates for PEC water splitting due to their visible light absorption and thermal stability. However, drawbacks such as low catalytic activity, charge carrier mobility and high recombination rates can be addressed through cation and anion doping for structural modification. Computational tools like density functional theory (DFT) are essential for optimizing the doped SBGMO structures, reducing experimental time and resources. This brief review examines properties such as band gaps, density of states, band structure, and adsorption energy in predicting the SBGMO structures before experimental testing. Optimizing these parameters improves visible sunlight absorption, sun to hydrogen efficiency, material’s catalytic activity and water adsorption energy, thereby addressing the drawbacks of SBGMO. Despite the narrow scope of the review, it provides insights into the comparison between the theoretical and experimental performance of the SBGMO and their modified doping structures. This study demonstrates that DFT-optimized structures can provide valuable guidance for material selection through real experimental work that overcomes DFT limitation and approximations.