Enhancing solar energy harvest by Cu2S/CuCl heteroarrays with enriched sulfur vacancies for photo-rechargeable pseudocapacitors

Abstract

The use of broadband light energy is important for enhancing photoenergy conversion. However, bifunctional materials that can efficiently harvest solar energy to assist electrochemical energy storage are difficult to prepare. Herein, copper foam (CF)-supported cuprous sulfide (Cu2S) heteroarrays (CS HAs) with enriched sulfur (S) vacancies (VS) were designed for photo-rechargeable pseudocapacitors. A direct hydrothermal sulfurization of CF first resulted in the growth of CS HAs with leaf-like heterostructures. Subsequent partial oxidation of S2− in FeCl3 aqueous solution enriched the VS within the leaf-like structures. In addition, CuCl and Cu2O were formed from Cu2S during FeCl3 treatment to derive a bifunctional photoelectrode with ternary components, thus further broadening the light absorption region. Thus, the optimal CS HAs have demonstrated areal capacitances of 1440−1048 mF cm−2 with the assistance of the photoelectric/thermal effects of light energy, delivering remarkable photoenhancements of 25%–35%. The asymmetrical pseudocapacitors fabricated from the optimal photoelectrodes delivered a high areal capacitance of 670 mF cm−2 after 6000 cycles, suggesting a promising application in transparent light-driven energy devices. [Figure not available: see fulltext.].