Recent advances in anode catalysts for waste valorization through hybrid water electrolysis: Towards sustainability beyond hydrogen production

In the pursuit of sustainable energy sources, considerable focus has been directed towards the hydrogen production using renewable energy-driven water electrolysis. The exploration of alternative anodic reactions, particularly incorporating wastes as electron donors, not only reduces energy consumption of water electrolysis but also extends sustainability beyond hydrogen production. This review highlights the significance of the chemical properties, widespread availability, and potential value-added prospects of wastes for their integration into hybrid water electrolysis systems. Recent advances on the role of anode catalysts in waste valorization are critically evaluated, focusing on promising waste streams such as hydrogen sulfide, crude glycerol, cellulosic wastes, and plastics. Among them, stability stands out as the primary challenge in the rational design of catalysts for sulfide valorization, while achieving enhanced product selectivity is a crucial consideration for catalysts involved in the valorization of organic wastes. Furthermore, the development of earth-abundant metal catalysts for waste valorization poses a shared challenge, necessitating a profound understanding of structure-activity relationship and the fine-tuning of the nanostructure, chemical composition, and electronic structure of catalysts.