Efficient charge carrler transfer from light harvesters to catalysts greatly determines the photocatalytic activity in an artificial photosynthesis (AP) system for solar hydrogen evolution.In this study,an AP system composed of xanthene dye as light harvester and cobaloxime molecular complex as catalyst,with TiO2 as electron relay,was designed for photocatalytic hydrogen evolution under visible light (λ ＞420hm).It was demonstrated that with cobaloxime molecule covalently linked onto the TiO2 electron relay,the resulting hybrid AP system exhibited much increased photocatalytic activity as compared to that without TiO2.The greatly increased photocatalytic activity should be due to the efficient electron transfer from xanthene dye as light harvester and cobaloxime molecular complex as catalyst,shuttled by the TiO2 electron relay,for the following water reduction reaction.The present study demonstrates a facile and feasible strategy to guide the design of high performance AP systems through the electron relay shuttled and promoted charge transfer process.