0D ultrafine ruthenium quantum dot decorated 3D porous graphitic carbon nitride with efficient charge separation and appropriate hydrogen adsorption capacity for superior photocatalytic hydrogen evolution

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 5; no. 7; pp. 2414 - 2425
• Main Authors: An, Pengfei, Zhu, Weihao, Qiao, Luying, Sun, Shichao, Xu, Yuyan, Jiang, Deli, Chen, Min, Meng, Suci
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 21.02.2021
• Subjects: Adsorption; Carbon nitride; Chemical reduction; Gibbs free energy; Hydrogen; Hydrogen evolution; Photocatalysis; Photocatalysts; Quantum dots; Quantum efficiency; Ruthenium; Separation; Surface chemistry; System effectiveness; Ultrafines; Water splitting
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d0dt03445b

Designing a Pt-alternative cocatalyst capable of dissociating HO-H bonds is of great significance yet challenging for the development of high-efficiency and cost-effective water splitting photocatalytic systems. In this study, we designed and constructed a 0D ultrafine ruthenium (U-Ru) quantum dot decorated 3D porous g-C 3 N 4 (3DpCN) nanohybrid (U-Ru/3DpCN) for photocatalytic hydrogen evolution, in which the U-Ru quantum dots act as cocatalysts accelerating the surface proton reduction reaction, and the 3D porous architecture assembled by 2D ultrathin nanosheets inherits a short charge diffusion distance and has a large specific surface area. Owing to these structural and physicochemical merits, the optimal photocatalyst U-1Ru/3DpCN achieves a superior hydrogen evolution performance of 2945.47 μmol g −1 h −1 under visible light with a high apparent quantum efficiency (AQE) of 9.5% at 420 nm, which is close to Pt-cocatalyst/3DpCN and better than most reported co-catalysts/g-C 3 N 4 photocatalytic systems. Experimental results indicate that the formed Schottky junction between U-Ru and 3DpCN contributes to efficient charge separation, and DFT calculations show that the Ru-cocatalyst/g-C 3 N 4 system has an appropriate hydrogen adsorption Gibbs free energy (Δ G H* ) of 0.24 eV, which are both responsible to improve the photocatalytic performance. This study provides a new way to develop excellent photocatalysts for hydrogen evolution by the integration of cost-effective Ru quantum dot cocatalysts with nanostructured semiconductors. Ultrafine Ru quantum dot decorated 3D porous g-C 3 N 4 (U-Ru/3DpCN) photocatalysts were prepared. The optimal photocatalyst U-1Ru/3DpCN achieves an excellent H 2 evolution of 2945.47 μmol g −1 h −1 under visible light with a high AQE of 9.5% at 420 nm.