Roles of experimental variables in optimised fabrication of microrecycled CuO-based photoelectrodes

Abstract

The recycling of electronic wastes into value-added nanostructures for sustainable photo-induced hydrogen generation has been shown to contribute towards the circular economy goals for zero-net emissions. For the desired photocurrent performance, it is imperative to understand and control every step during the synthesis of photoelectrodes and the assembly of photoelectrochemical cells. Despite a large number of researches on photocatalytic performances for semiconducting materials that have been reported to date, there appear to be only limited systematic studies regarding the process of electrode fabrication. The present work firstly reports on the synthesis of CuO-based nano-needles derived from waste flexible printed circuit boards (FPCBs), followed by a systematic investigation on the electrode fabrication parameters that significantly contribute to the photoelectrode performances. These parameters include conductive and binding agents, dispersion media, photocatalyst loading, illumination direction, type and thickness of the substrate, sweeping rate under illumination, and type of charged species (i.e. media and species concentration) in photoelectrolysis. This work provides an instructive guideline to address the most frequently experimental challenges as well as highlights the disregarded, yet critical, criteria in the future development of photoelectrodes. Further, the present work suggests that microrecycling and reforming require to be in compliance with value-addition manufacturing and performance.