High efficient noble metal free Zn(O,S) nanoparticles for hydrogen evolution

Abstract

Noble metal-free zinc oxysulfide (Zn(O,S)) nanoparticles for H2 evolution had been facilely synthesized by a low-cost chemical reaction at low process temperature of 70–90 °C with zinc acetate dihydrate as the zinc source and different amounts of thioacetamide as the sulfur precursor. The as-prepared Zn(O,S) had a nano crystallite size of 3–10 nm and formed aggregates. Low temperature process has led to the difficulty in forming well-crystalline nanoparticles, therefore the ionic bonding is weaker as compared to the high temperature one. Due to the entropy-controlled reaction, Zn(O,S) with different compositions, phases, and bandgaps was formed and proposed to have a three-dimensional multibandgap-quantum-well (3D MQW) band structure, as supported by the selected area electron diffraction of high resolution transmission electron microscopy. Photo reduction of Cr6+ was initially performed for our materials selection. The photocatalytic hydrogen evolution reaction (HER) of Zn(O,S) in different kinds of solutions under low power UV lamps (the intensity is 0.088 mW/cm2 or approximately 1/40 times UV light intensity of sunlight) was executed. A high efficient hydrogen evolution rate of 213 μmol/g h watt was achieved by considering the input light power. The active surface oxygen anion-involved photocatalytic mechanism for HER is proposed, which was derived from the reversible change in Zn(O,S) color and the results from HER reactions in different solutions.