Recent Advances in Sensitized Photocathodes: From Molecular Dyes to Semiconducting Quantum Dots

Abstract

The increasing demand for sustainable and environmentally benign energy has stimulated intense research to establish highly efficient photo‐electrochemical (PEC) cells for direct solar‐to‐fuel conversion via water splitting. Light absorption, as the initial step of the catalytic process, is regarded as the foundation of establishing highly efficient PEC systems. To make full use of visible light, sensitization on photoelectrodes using either molecular dyes or semiconducting quantum dots provides a promising method. In this field, however, there remain many fundamental issues to be solved, which need in‐depth study. Here, fundamental knowledge of PEC systems is introduced to enable readers a better understanding of this field. Then, the development history and current state in both molecular dye‐ and quantum dot‐sensitized photocathodes for PEC water splitting are discussed. A systematical comparison between the two systems has been made. Special emphasis is placed on the research of quantum dot‐sensitized photocathodes, which have shown superiority in both efficiency and durability towards PEC water splitting at the present stage. Finally, the opportunities and challenges in the future for sensitized PEC water‐splitting systems are proposed.

A nanostructured NiO/cubic SiC p–n heterojunction photoanode for enhanced solar water splitting

“…The utilization of abundant sunlight is an ingenious solution to the global energy crisis and environmental issues. [1][2][3][4] Solardriven photoelectrochemical (PEC) water splitting provides a promising method for conversion of the intermittent solar energy into renewable and storable chemical energy in the form of H 2 . [4][5][6][7][8][9] Since the pioneering work of A. Fujishima and K. Honda in 1972, oxides such as TiO 2 , WO 3 , Fe 2 O 3 , and III-V materials have been extensively studied for the PEC water splitting.…”

Artificial photosynthesis: opportunities and challenges of molecular catalysts

“…Ideal light absorbers, with broad absorption in the solar spectrum, stable excited states and high charge carrier mobility, and efficient catalysts, with high intrinsic activity and stability, are the two essential components to realize AP. Photosensitizers or light absorbers, such as molecular dyes, 19,32,33 semiconductors 34 and quantum dots, 35,36 are needed to absorb the light and generate the charge separation. Moreover, efficient catalysts are the other key.…”

Rational Design of 3D Hierarchical Ternary SnO2/TiO2/BiVO4 Arrays Photoanode toward Efficient Photoelectrochemical Performance

“…The band alignment was confirmed by the optical bandgap from the UV-vis absorption spectra ( Figure S14b, Supporting Information) and the valence band edges measured by UPS. [61][62][63] Under light excitation, both BiVO 4 and TiO 2 can absorb photons and generate electron-hole pairs. [61][62][63] Under light excitation, both BiVO 4 and TiO 2 can absorb photons and generate electron-hole pairs.…”