| It is of great significance to produce clean hydrogen energy via solar photocatalytic water splitting for the sustainable development of human society. The hard and hot-point on solar photocatalytic hydrogen production studies is to produce visible-light-active photocatalyst. In this paper, to improve the efficiency of water photolysis reaction, different kinds of templates are tried to fabricate series nano-porous InVO4 photocatalys which are visible light active.Two different routes were approached to develop nano-porous InVO4 photocatalys: on the one hand, to prepare nano-porous InVO4 by means of the surfactant-templating hydrothermal method using cationic surfactant CTAB or nonionic surfactant P123, DDA, TDA and HDA as"soft-template"; on the other hand, considering the difficulties to obtain well-ordered porous structure caused by the possible collapse of porous wall during the template removing process under high temperature, to fabricate supported InVO4 by hydrothermal method using CNTs and SBA-15 as"hard-template". The crystal structures, morphologies, surface areas, and photon absorption properties of the synthesized catalysts were characterized by means of XRD, TEM, SEM, SAED, BET and UV-Vis techniques, respectively. The effects of precursors to template mol ratio, loading amounts, pore size, pH value, crystallization temperature, crystallization time, solvent extraction and calcination temperature on the physical and chemical properties of the synthesized samples were deeply studied and discussed. The photocatalytic activities of the nano-porous InVO4 photocatalys for water splitting to hydrogen were evaluated under UV and visible light irradiation. The effects of loading NiOx and adding sacrificial agents on the hydrogen evolution efficiency were discussed,emphatically.The experimental results showed that there are two different morphologies of the series InVO4 photocatalyst synthesized by soft-template method: InVO4-CTAB shows a typical wormhole-like structure, InVO4-P123 has a layered structure represented by a multi-layered aggregation, while InVO4-RDA exists as nano-particles. Through controlling the calcination temperature, one could generate InVO4 with different crystal structures: single-phase monoclinic when being calcined at 600 oC, single-phase orthorhombic when being calcined at 900 oC, and a mixed crystal phases when being calcined at 700 oC and 800 oC. The surface areas of InVO4-CTAB and InVO4-P123 reach 65.7 m2 g-1 and 79.5 m2 g-1, respectively. By comparing with the InVO4 catalyst fabricated by the solid-state synthesis method, the visible light absorption ability of the nano-porous InVO4 catalyst in this paper are much improved, and the absorption threshold extended to 800 nm. InVO4-CTAB, InVO4-P123 and InVO4-HDA show high photoactivity to pure water splitting reaction under visible light irradiation, and the average H2 evolution rate within 4 h is 100.4μmol g–1 h–1, 120.5μmol g–1 h–1, 65.8μmol g–1 h–1, respectively. The rate is much improved after loading NiOx on the catalyst.After loading InVO4 on the surface of CNTs and SBA-15 hard-templates, the pore structure of CNTs and SBA-15 kept very well and the InVO4 particles scattered on their surface uniformly. The surface area of InVO4/CNTs and InVO4/SBA-15 reach 102.1 m2 g?1 and 213.1 m2 g-1, respectively. Under visible light irradiation, the average H2 evolution rate from pure water over 20 wt.% InVO4/CNTs-2040 and 50 wt.% InVO4/SBA-15 within 4 h is 156μmol g–1 h–1 and 202.4μmol g–1 h–1. The evolution rate is improved markedly in the presence of methanol. The high photocatalytic activity of InVO4/CNTs and InVO4/SBA-15 is related to the high surface area and the crystal structure.The quantum efficiency and energy conversion efficiency of the nano-porous InVO4 photocatalys in this paper were calculated and analyzed. The quantum efficiency decreased by the following order: InVO4/SBA-15, InVO4/CNTs-2040, InVO4- P123, InVO4- CTAB,InVO4- HAD, InVO4- TDA, InVO4-DDA. In which, the 50 wt.%InVO4/SBA-15 catalyst shows the best photoactivity, and its quantum efficiency and energy conversion efficiency when split methanol solution under visible light irradiation reach 10.54% and 3.81%, respectively. The influence regularity of hydrogen production performance are summarized from several aspects, including templates, crystal structures, photon absorption performance, assist-catalysts and sacrifice reagents, etc. Some possible routes and ideas to further improve the quantum efficiency and the energy conversion efficiency are provided in the end.
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