Sulfur-substituted and zinc-doped In(OH)3: A new class of catalyst for photocatalytic H2 production from water under visible light illumination

Sulfur-substituted In(OH)3 [hereafter denoted as In(OH)ySz] and Zn-doped In(OH)ySz [hereafter denoted as In(OH)ySz:Zn] are synthesized in an aqueous solution of ethylenediamine via the hydrothermal method. The photoactivities of these catalysts for H2 production are investigated in the presence of Na2S and Na2SO3 sacrificial reagent under visible light illumination (image). The absorption edge of In(OH)ySz shifted monotonically from 240 nm for In(OH)3 to 570 nm for In(OH)ySz when the atomic ratio of S/In in the synthesis solution is increased from 0 to 2.0. But the absorption edge of In(OH)ySz:Zn shifted from 570 to 470 nm as the atomic ratio of Zn/In in the synthesis solution was increased from 0 to 1.0. The catalyst In(OH)ySz is active for H2 production, with an average rate of H2 of 0.9–1.8 μmol/h, under visible light illumination. The photoactivity of In(OH)ySz is enhanced by doping with Zn2+. The rate of H2 production is 35.8 and 67 μmol/h on 2wt% Pt-loaded In(OH)ySz:Zn catalyst when image and 0.5, respectively, corresponding to a quantum efficiency of 0.32 and 0.59% at image, respectively.