Enhanced Photocatalytic H2-Production Activity of g-C3N4 Nanosheets via Optimal Photodeposition of Pt as Cocatalyst

Photocatalytic H2 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 H2-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 μmol 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.