Effect of RGO/Zn_:XCd_{1- x}S crystalline phase on solar photoactivation processes

A series of reduced graphene oxide/Zn_xCd_1-xS (RGO/Zn_xCd_1-xS) nanocomposites (0 < x < 1) with different ratios of Zn/Cd were synthesized via a facile hydrothermal route under optimized experimental conditions and were carefully characterized by various techniques. Because very little is known about the morphology, specific surface area, and crystal phase effects of RGO/Zn_xCd_1-xS crystals on their photoresponsivity, field-emission scanning electron microscopy (FE-SEM), BET surface area analysis and X-ray diffraction (XRD) data were studied to investigate their effects on photoactivity. Based on the results, a crystal phase transition from a cubic phase in RGO/Zn_0.9Cd_0.1S to a hexagonal wurtzite phase in RGO/Zn_0.8Cd_0.2S nanocomposites occurs and the crystalline phase is the main factor influencing the photoresponsivity of RGO/Zn_xCd_1-xS nanocomposites in photodegradation and photoelectrochemical (PEC) processes under visible light irradiation. According to the results, the RGO/Zn_0.8Cd_0.2S nanocomposite with the hexagonal crystal phase revealed better photocatalytic activity (k = 9.4 × 10^-3 min^-1) and PEC response (∼2.0 mA cm^-2) in comparison with the cubic crystal phase.