CoOOH/CdIn2S4 Film Photoanodes Driving Unbiased Tandem Cells towards Simultaneously Efficient Oxidation of Benzyl Alcohol and Selective Generation of Ethanol from CO2 Reduction

Abstract

In unbiased tandem cells, the production of C2+ products from CO2 reduction on cathode is dependent on the effective supply of charge from photoanode. At present, the development and understand of efficient photoanodes remain challenging. CoOOH nanosheets coupled CdIn2S4 film (CoOOH/CdIn2S4) was investigated as photoanode to drive solar benzyl alcohol oxidation. Relative to CdIn2S4 photoanode, lower carrier recombination, better activity and faster kinetics were achieved on CoOOH/CdIn2S4 photoanode for benzyl alcohol oxidation into benzaldehyde. Several investigations jointly revealed that the oxidation of benzyl alcohol into benzaldehyde on CoOOH/CdIn2S4 photoanode is mediated with the formation of hydroxyl radicals, and the slight change of β-CoOOH into γ-CoOOH. Additionally, CoOOH coupling with CdIn2S4 is more energetically favourable for benzyl alcohol oxidation into benzaldehyde. Consequently, CoOOH/CdIn2S4 photoanode be of high Faraday efficiency and selectivity for benzyl alcohol oxidation. In the CoOOH/CdIn2S4 photoanode-Cu2O cathode unbiased tandem cell, benzaldehyde and ethanol can be selectively produced from benzyl alcohol oxidation and CO2 reduction, respectively. Additionally, the CoOOH/CdIn2S4 photoanode can work stably to drive the unbiased cell, and 88% of its initial activity can be maintained after 4 h of reaction.