Cadmium sulfide quantum dots sensitized tin dioxide–titanium dioxide heterojunction for efficient photoelectrochemical hydrogen production

Abstract CdS quantum dots (QDs)-sensitized branched TiO 2 /SnO 2 heterojunction (B–SnO 2 NF–CdS) with suitable combination of band gap and band alignment constitutes a promising architecture for photoanode for H 2 generation. This novel structure combines the conflicting advantageous features of slow interfacial electron recombination, long electron life time, fast electron transport and visible light absorption. Remarkable photocurrent density of 3.40 mA cm −2 at zero bias (vs. standard calomel electrode) has been obtained in a three electrode configuration, more than two times as large as that of TiO 2 –CdS photoanode. The B–SnO 2 NF–CdS yields a high maximum applied bias photon-to-current efficiency (ABPE) of 2.18% at an applied bias of ∼0.316 V vs. reversible hydrogen electrode (RHE), indicating excellent hydrogen generation performance at low bias. Moreover, on the basis of experimental results, we ascribe the remarkable “dark current/voltage” to the effect of primary cell. The influence of the primary cell on PEC hydrogen production is discussed.