Recent avenues in the photocatalytic splitting of water for eco-friendly hydrogen production

Fossil fuel-driven carbon emissions are destabilizing the global climate. The COP28 conference, recently held in Dubai, UAE, under the UNCCC, marked a pivotal moment by signaling the "beginning of the end" for fossil fuels, advocating for a swift and equitable transition with significant emission reductions and increased financial support. Photocatalysts offer immense potential for sustainable applications such as hydrogen production and organic pollutant degradation. However, challenges persist, including limited visible-light absorption due to large bandgaps, rapid recombination of charge carriers, susceptibility to corrosion, lack of selectivity, and partial catalytic activity for specific reactions. This review examines the use of various photocatalysts for hydrogen production via water splitting. It discusses the reaction mechanisms involved and the different types of photocatalysts, including metal oxides, carbon-based materials, semiconductors, and metal-organic frameworks (MOFs). Recent advancements in photocatalyst technology have focused on strategies such as bandgap engineering, co-catalyst deposition, surface modification, heterojunction formation, and co-catalyst engineering. These approaches aim to improve photo- catalytic performance by enhancing activity, broadening the absorption range, and increasing charge separation efficiency. Techniques like doping with foreign elements, modifying surface morphology, creating heterojunctions with other semiconductors, and adjusting bandgaps have shown promise in addressing these challenges. Moreover, studies have highlighted the influence of factors such as doping, crystal structure, particle size, and surface morphology on photocatalytic efficiency. These innovations collectively improve the effectiveness, selectivity, and stability of photocatalysts, positioning them as strong candidates for sustainable energy solutions and environmental remediation. Finally, this study outlines challenges, recent progress, and offers insights into future directions for enhancing photocatalyst efficiency to address global energy and environmental needs.