Design and development of nanostructured photocatalysts for large-scale solar green hydrogen generation

The production of clean hydrogen through artificial photosynthesis is the most intriguing research topic that offers hope for meeting the world's energy demands. The evolution of green hydrogen via visible light-driven photocatalysis is challenging but feasible. Photocatalytic solar power systems primarily rely on utilizing the complete range of solar spectrum. The synthesis of an optimal photocatalyst should address all the influencing parameters with an efficient scaling method, which remains yet to be elucidated despite several advancements in photocatalytic water-splitting applications. Real-time solutions are necessary to overcome the lack of photocatalytic efficacy of semiconducting nanomaterials in solar-powered systems. In addition to the proposal of designing solar-powered systems for hydrogen generation, this review paves the way for highlighting the difficulties associated with water reduction methods. It also offers some strategies to improve charge separation and migration in a semiconducting photocatalyst by enhancing light absorption and altering their band positions. Moreover, a cost-effective, eco-friendly, and photostable heterogeneous nanocatalyst must be designed for visible light-harvesting water-splitting processes. This article reports various nanomaterial-based photocatalysts, which act as the base surface for photocatalytic solar water splitting. These include oxides, chalcogenides, and nitrides of metals, noble metals, plasmonic metals, ultrathin 2D covalent-organic frameworks (COFs), metal-organic frameworks (MOFs), and metal-free polymeric graphitic carbon nitrides. The integration of multi-component nano-materials can be more appropriate than single-component photocatalysts to maximize their catalytic activity. Thin-film photocatalysis is considered the most effective method for increasing hydrogen production rates compared to powder suspension-based photocatalysis. This article presents the latest advancements in thin film-based photocatalytic technology, outlining all the critical factors, prerequisites, and techniques for thin film preparation. Future research on advanced photocatalysis focuses on harvesting green hydrogen for in situ carbon dioxide reduction, fine chemical synthesis, nitrogen fixation, and hydrogen peroxide synthesis. Experimentally, photocatalytic solar-powered systems utilize natural sun light. However, the synthesis of ideal photocatalysts via effective scaling approaches remains a challenge. This paper paves the way for finding solutions and designing a practical solar-powered system for green hydrogen production. Thin films mediated photocatalytic hydrogen production is the recent intriguing challenge to overcome the global energy demand. By development of fine nanomaterials and preparation of thin films hydrogen production can be increased to large scale.