Photogenerated charge separation at BiVO4 photoanodes enhanced by a Ag-modified porphyrin polymer skeleton

Huiqin Ye; Hui Xiao; Rongfang Zhang; Shengya Zhang; Ze Wang; Wei Luo; Ruixiu Xie; Yanjun Feng; Xiaoquan Lu

doi:10.1039/d3dt01728a

Photogenerated charge separation at BiVO₄ photoanodes enhanced by a Ag-modified porphyrin polymer skeleton

Dalton Trans. 2023 Aug 8;52(31):10911-10917. doi: 10.1039/d3dt01728a.

Authors

Huiqin Ye^{1

2}, Hui Xiao^{1

2}, Rongfang Zhang^{1

2}, Shengya Zhang^{1

2}, Ze Wang^{1

2}, Wei Luo^{1

2}, Ruixiu Xie^{1

2}, Yanjun Feng^{1

2}, Xiaoquan Lu^{1

2}

Affiliations

¹ Key Laboratory of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China. luxq@nwnu.edu.cn.
² Key Laboratory of Water Security and Water Environment Protection in Plateau Intersection, Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China.

PMID: 37489642
DOI: 10.1039/d3dt01728a

Abstract

Bismuth vanadate (BiVO₄) has been considered a promising photoactive material in photoelectrochemical (PEC) water-splitting systems. However, the performance of BiVO₄-based photoanodes is currently unsatisfactory, indicating the need for new architectural designs to improve their efficiency. In this paper, a porphyrin-phosphazene polymer (THPP-HCCP) was synthesized with a sizeable conjugated structure, and Ag particles were deposited on its surface as an organic-inorganic composite interface improvement layer. The deposition of the composite polymer film on BiVO₄ resulted in a significant increase in photocurrent density, reaching up to 2.2 mA cm^-2 (1.23 V vs. RHE), almost three times higher than pristine BiVO₄, which benefits from the synergistic effect of Ag nanoparticles and porphyrin-phosphazene. Furthermore, photophysical and intensity-modulated photocurrent analysis demonstrated that the Ag-THPP-HCCP heterostructures could broaden the light-absorbing range and facilitate hole transfer to the semiconductor surface, resulting in an improved water oxidation process. The dynamic charge transport behavior of Ag-THPP-HCCP/BiVO₄ was investigated using scanning photoelectrochemical microscopy, which showed that the rate constant (K_eff) exhibits an almost 4-fold increase compared to pristine BiVO₄, indicating a significant improvement in the transport of photogenerated holes. This experiment presents a novel strategy for designing high-efficiency polymer-based photoanodes.