"114" oxides have shown intriguing physical properties while their performance in photocatalysis has not yet been reported probably due to the instability in aqueous solution. YBaZn3GaO7 is an exception, which is stable and indeed shows observable photocatalytic H-2 evolution (similar to 2 mu mol/h/g) in methanol aqueous solution under UV light. This activity was enhanced to 23.6 mu mol/h/g by a full replacement of Y3+ by Sc3+. Optical absorption spectra and theoretical calculations show no significant difference upon Sc3+-doping. Instead, a systematic analysis of the structure evolution by Rietveld refinements for Y1-xScxBaZn3GaO7 (0 <= x <= 1) suggests that the increase of the catalytic activity is likely due to recombination rate of e(-) and h(+). In detail, Sc3+ substitution adjustment of the Zn2+/Ga3+ occupancy behaviors in tetrahedra to 118.2 itmol/h/g in methanol solution and 42.9 innol/h/g relatively less investigated nonmagnetic "114" oxides were, for water reduction. the decrease of the structural defects and thus the lower level of leads to a shrinkage of YO6 octahedra, and successively the sites. The photocatalytic H-2 evolution rate was further optimized in pure water for 1 wt % Pt -loaded ScBaZn3GaO7. Here, the the first time, proved to be good candidates for photocatalytic water reduction.