Enhanced Photocatalytic H-2-Production Activity of g-C3N4 Nanosheets via Optimal Photodeposition of Pt as Cocatalyst

Photocatalytic H-2 production plays an important role in alleviating fossil fuel crisis and constructing a sustainable world. Graphitic carbon nitride nanosheets (CNS), coupled with cocatalyst platinum (Pt) and hole sacrificial agent triethanolamine (TEOA), often show excellent H-2-production activity. However, the question on maximizing Pt amount in this given TEOA-contained system still remains unsolved. Herein, it was found that the order of adding TEOA into the reaction system before or after the photodeposition of Pt had a significant effect on photocatalytic hydrogen production over CNS. Specifically, the content of Pt was lower when TEOA was added beforehand, implying that a strong interaction existed between the Pt-precursor H2PtCl6 and TEOA, thus curbing the photoreduction to metallic Pt. Therefore, a roughly 4-fold increment in hydrogen production activity (4210.8 vs. 972.2 mu mol h(-1) g(-1)) was obtained by merely swapping the sequence of the addition of TEOA. Moreover, the apparent quantum efficiency (AQE) at 420 nm wavelength was also quadrupled from 0.63% to 2.4%. Simultaneously, the mechanism behind this phenomenon was thoroughly investigated. This work highlights the importance of experimental design and provides a facile approach in fully utilizing noble metallic Pt.