Graphene oxide partially exfoliated from carbon cloth: A new Paradigm of photocathode for Solar–Driven photoelectrochemistry

Abstract

A critical factor limiting the photoelectrocatalytic reaction rate over semiconductors is severe photogenerated charge–carrier recombination, which is well–circumvented in this study by using graphene oxide (GO) partially exfoliated from carbon cloth (CC) as the photoelectrode. A kinetic model is proposed for the first time to rationalize the outstanding photoelectrochemical activity of GO/CC by accounting for the photoexcited charge carrier generation induced by harvesting of broadband sunlight mostly by GO. The photogenerated electron–hole pairs are thereby close to the GO/CC–electrolyte liquid junction and are rectified by surface band bending to flow in opposite directions. The charge recombination is hence largely suppressed and further quenched considering the high–lying conduction band extremum of GO, which favors injection of the photoexcited electrons into the electrolyte. As an important result of efficient charge separation, the photogenerated charge carriers relax mostly via the reaction with H2O2 in the electrolyte, as evidenced by the steady–state photocurrent density of GO/CC depending linearly on the light intensity and by the transient time constant of the time–resolved photocurrent response of GO/CC to chopped solar irradiation being primarily dictated by the diffusion and dissociative adsorption rate of H2O2 on GO/CC.