Photocatalytic Hydrogen Production from Aqueous Na2S + Na2SO3 Solution with B-Doped ZnO

Abstract

Nonmetal (N and B) doped ZnOs were developed for hydrogen production from aqueous sacrificial anion, S2––SO32–, solution. In the present work, N- and B-doped ZnO nanomaterials were successfully prepared by a simple, effective, high yield, and low cost mechanochemical combustion technique, with addition of urea or boric acid to a zinc acetate and oxalic acid mixture. The prepared oxides were characterized by X-ray diffraction (XRD), BET surface area analysis, X-ray photoelectron spectroscopy (XPS), scanning electron spectroscopy (SEM), UV–visible diffuse reflectance spectroscopy (UV-DRS), and photoluminescence spectroscopy (PL). The photocatalytic hydrogen production was observed with 880 μmol g–1 for undoped ZnO with 0.4 M Na2S + 0.4 M Na2SO3 solution, due to in-situ formation of a ZnS/ZnO heterojunction. The doped ZnO materials had better activity than undoped ZnO. The photocatalytic H2 evolution with B-doped ZnO (1730 μmol g–1) was larger compared with those obtained with N-doped ZnO. The photocatalytic H2 productions with B-doped ZnO were affected by parameters such as calcination temperature, calcination time, and doping concentrations. The B-doped ZnO demonstrated higher activity due to small particles size, large surface area, and reduction of electron–hole recombination.