Effects of Periodic Pore Ordering on Photocatalytic Hydrogen Generation with Mesoporous Semiconductor Oxides

Abstract

Crystalline and 3D continuous mesoporous quaternary CsTaWO6 semiconductors are prepared with different degrees of long-range periodic order and local order, respectively, to investigate the influence of periodic pore order on the photocatalytic performance in hydrogen evolution of mesoporous photocatalysts. The degree of long-range order of the mesopores is changed by modifying the ratio between metal precursors and soft polymer template poly(isoprene-b-styrene-b-ethylene oxide) (PI-b-PS-b-PEO; ISO) in the sol–gel synthesis. Long-range periodic order is found to have no appreciable advantage compared with an only locally ordered continuous pore system. On the contrary, nonperiodically ordered mesopores result in higher activity toward photocatalytic hydrogen evolution, even with slightly smaller pore diameter and lower cumulative pore volume. Most importantly, it is shown that pore connectivity and heterogeneous pore systems in mesoporous photocatalysts play a major role for hydrogen evolution when other parameters are confirmed to be not rate limiting.