Ag nanocubes-decorated ammonium hydroxide-treated carbon nitride to improve photocatalytic H2O2 production and fuel cell performance

A novel photocatalyst is designed by surface modification and cocatalyst loading of graphitic carbon nitride (g-C3N4) with ammonium hydroxide and silver nanocubes (AgNCs), respectively. The synergistic effect of the modification in the intralayer of g-C3N4 and surface plasmon resonance (SPR) bands of AgNCs significantly enhances the migration and separation efficiency of photo-induced charge carriers. A nickel mesh coated with photocatalyst and the carbon paper loaded with pristine g–C3N4–mixed iron phthalocyanine (FeIIPc) used as the photoanode and cathode, respectively, are constructed for the self-powered photoelectrochemical cell, which exhibits the maximum power density of 0.74 mW cm−2. The AHCN/AgNCs-based cell reveals approximately a 3.1-times enhancement in maximum power density compared with the pristine g–C3N4–based cell. In addition, the photocatalytically generated H2O2 (chemical energy) can be stored in water, and then used as fuel by the connection of two electrodes in the dark. After the fuel cell is operated for 12 h, the specific capacitance retention rate still maintains as high as 57.2 %, which is the greatest retention rate in comparison with the previously reported H2O2 fuel cell systems. Our work offers a feasible opinion on how to improve the visible light utilization of semiconductors by tuning the intralayer properties and loading plasmonic metal.