Controlled photodeposition of Pt onto TiO2-g-C3N4 systems for photocatalytic hydrogen production

Platinum (0.5 wt. %) was photodeposited on g-C3N4-TiO2 systems using UV or Vis light. Different absorption by semiconductors seemed to somehow influence resulting platinum particle size and distribution. Thus, lower platinum particle sizes were obtained on g-C3N4 utilizing visible light and on TiO2 using UV radiation. Furthermore, there was a preferential platinum photodeposition on g-C3N4 or TiO2, more evident in physical mixtures of both semiconductors, depending on radiation source being visible or UV light, respectively. The solids were tested for hydrogen photoproduction using triethanolamine as the sacrificial agent. g-C3N4 synthesis on P25 TiO2 allowed the effective formation of a heterojunction (as determined by UV–vis and EPR). Subsequent platinum photodeposition resulted in solids yielding ca. 5100 μmol·g−1·h−1 H2 under visible light. This represents a ca. 7-fold increase in activity as compared to the physical mixture of platinum-containing semiconductors and a 2-fold increase as compared to simultaneous incorporation of platinum to the reaction medium.