Photocatalytic H_2 evolution of selective phase CZTS synthesized by ultrasonic spray pyrolysis method

摘要

Cu_2ZnSnS-4 (CZTS), with a direct bandgap of 1.5 eV, is a primary candidate material for solar energy conversion applied in both photovoltaics and photo-catalysis due to its tremendous reserves and environmental friendly components. Though the utilization of CZTS with phases of kesterite and wurtzite are extensive, until now, the synthesis and growth procedure of both phases are not clearly understood. In this work, we succeed in synthesizing CZTS micro-spheres with controlled phase through a facile method-ultrasonic spray pyrolysis (USP). By choosing ammonium thioglycolate and L-cysteine as sulfur source, which were found to be the key factor in the phase formation process, CZTS microspheres can be prepared in kesterite phase and wurtzite phase, respectively. After exposing the prepared CZTS microspheres under the Xe lamp irradiation, we found an apparently phase-dependent photocatalytic hydrogen evolution, in which the performance of kesterite phase CZTS sample was almost 2 times as high as that of wurtzite CZTS sample.