Efficient solar-to-chemical conversion with chlorine photoanode

•An 8% efficient photoanode is here implemented based on chlorine evolution reaction in saturated NaCl solution.•Photocurrent rises at 0.6 V (vs. RHE), and the RuO2/TiO2/Si photoanode produces Cl2 exclusively without detectable O2.•Photoelectrochemical tests are combined with on-line mass spectroscopy for product detection.

The photoelectrochemical water splitting is an artificial photosynthetic approach that could provide a sustainable supply of clean energy, however, the sluggish kinetics of the oxygen evolution reaction (OER) has been a bottleneck to the solar-to-chemical conversion. Here we report an implementation of 8% efficient photoanode based on the photoelectrolysis of saturated NaCl solution. Replacing the OER with the chlorine evolution reaction (CER) has transformed both the thermodynamic basis and the kinetic process of the photoelectrolysis, more chemical energy can be produced with much less driving force. The RuO2/TiO2/n-Si photoanode exhibits a high rate of photoelectrochemical conversion (35 mA/cm2 at equilibrium potential), which steadily and exclusively produces Cl2 without detectable O2.

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