Chinese Journal of Catalysis ›› 2018, Vol. 39 ›› Issue (3): 502-509.DOI: 10.1016/S1872-2067(17)62943-7

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Photocatalytic water oxidation over BiVO4 with interface energetics engineered by Co and Ni-metallated dicyanamides

Yi Shang, Fujun Niu, Shaohua Shen   

  1. International Research Centre for Renewable Energy, State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, China
  • Received:2017-09-25 Revised:2017-10-29 Online:2018-03-18 Published:2018-03-10
  • Contact: 10.1016/S1872-2067(17)62943-7
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (51672210, 51323011, 51236007).

Abstract:

Photocatalytic water oxidation based on semiconductors usually suffers from poor charge transfer from the bulk to the interface, which is necessary for oxygen generation. Here, we construct a hybrid artificial photosynthesis system for photocatalytic water oxidation. The system consists of BiVO4 as the light harvester, a transitional metal complex (M(dca)2, M=Co, Ni, dca:dicyanamide) as the water oxidation catalyst, and S2O82- as a sacrificial electron acceptor. The system exhibits enhanced oxygen evolution activity when M(dca)2 is introduced. The BiVO4/Co(dca)2 and BiVO4/Ni(dca)2 systems exhibit excellent oxygen evolution rates of 508.1 and 297.7 μmol/(h·g) compared to the pure BiVO4 which shows a photocatalytic oxygen evolution rate of 252.2 μmol/(h·g) during 6 h of photocatalytic reaction. Co(dca)2 is found to be more effective than Ni(dca)2 as a water oxidation catalyst. The enhanced photocatalytic performance is ascribed to the M(dca)2-engineered BiVO4/electrolyte interface energetics, and to the M(dca)2-catalyzed surface water oxidation. These two factors lead to a decrease in the energy barrier for hole transfer from the bulk to the surface of BiVO4, which promotes the water oxidation kinetics.

Key words: Metal complex, BiVO4, Water oxidation, Photocatalysis, Interfacial kinetics