Semiconductor-based photoelectrochemical (PEC) hydrogen production from water represents an attractive approach for sustainable fuel production. In a PEC device, the semiconductor acts both as a photon harvester and as a catalytic surface for interfacial hydrogen evolution from water. For optimal efficiency, the semiconductor band gap must be matched to the solar spectrum to maximize collection, and the valence and conduction band edges should closely match the redox potentials of water. Recognizing this, past efforts have concentrated on engineering the band gap and level alignment to the redox potential of water. Nevertheless, although results have demonstrated that one can achieve sufficiently high solar-to-fuel conversion efficiency, this efficiency has come at the expense of short device lifetime due to fast degradation of the electrode. Further progress has been limited by a poor fundamental understanding of the hydrogen evolution and corrosion processes at the electrode-water interface.
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