Impact of catalyst reuse on hydrogen production from agricultural waste electrolysis: An experimental investigation

Hydrogen production from agricultural waste via biomass electrolysis remains underexplored. Progress toward continuous-flow operation is needed, particularly because catalyst reuse is a major challenge affecting economic viability. This research studies two primary agricultural wastes (Spent Mushroom Compost, SMC, and Poultry Litter, PL) as feedstock for hydrogen generation using an H-type proton exchange membrane electrolysis cell (H-PEMEC). The work focuses on phosphomolybdic acid (PMo12) as a catalyst and redox mediator without additional filtration or separation, requiring only the addition of new feedstock every cycle. In the first cycle, SMC and PL produced 27.5 mL and 22.7 mL of hydrogen per 0.5 g of feedstock, respectively, with SMC showing a 28.9% higher conversion efficiency (defined as H2 produced with respect to H2 present in the feedstock). Both feedstocks achieved 54-60% reductions in electrical energy consumption per kg of H2 produced compared to water electrolysis. The reusability of PMo12 was further evaluated using SMC. Without replacing the proton exchange membrane or the cathodic solution (H3PO4), PMo12 enabled 54.2 mL H2 per 0.5 g of feedstock in the 15th cycle, demonstrating that maintaining the same catalyst amount across cycles enhances its effectiveness as both a redox mediator and charge carrier. These results indicate that continuous operation requires less catalyst than batch processing while achieving higher hydrogen yields.