Chemical synthesis of ternary silver-indium selenide (AgInSe2) nanopowders in ethanol bath for photoelectrochemical hydrogen production

In this study, a simple and low cost process for the preparation of silver-indium-selenide (AgInSe2) photoanodes was reported. The influence of [In]/[Ag] ratios in reaction solutions on their phases, electrical, and photoelectrochemical activities was investigated. AgInSe2 nanopowders were first prepared in an ethanol bath with reaction time of 600s and temperature set at 70 degrees C. These nanopowders were then prepared as the ink for the deposition of AgInSe2 samples on substrates. Average particle size of 9.12 nm for all AgInSe2 nanopowders was observed using a transmission electron microscopy. X-ray diffraction patterns and energy dispersive spectra of these AgInSe2 samples showed that their crystal phases changed from the tetragonal-AgInSe2 to the tetragonal-AgInSe2 and AgIn5Se8 mixing phases at the [In]/[Ag] ratio of 2.01 in sample. Direct band gaps of AgInSe2 samples were located between 1.02-1.22 eV, respectively. Their flat band potentials were verified from -0.82 to -0.91 V vs. Ag/AgCl in an aqueous 0.35 M Na2S + 0.25 M K2SO3 electrolyte. The maximum photoelectrochemical performance of the AgInSe2 photoanode in various electrolytes was observed with the [In]/[Ag] ratio of 2.01 in sample. These results showed that the simple chemical synthesis AgInSe2 photoanode might have further application in solar-driven hydrogen production.