Synergetic NIR responsive plasmonic CuxS Nanodisks on CuO photocathodes for photo-electrochemical water splitting

Solar energy is a promising source for producing renewable hydrogen and harvesting the near infrared(NIR~52%) radiation. Herein, we synthesized CuxS nanodisks(NDs) with characteristic LSPR absorption in NIR, coupled with CuO NPs(Eg 1.6 eV) fabricating CuO/CuxS NDs photocathode for PEC water splitting. CuO/CuxS NDs delivered higher J, ABPE in alkaline (-10.3 mA cm-2, 3% at 0.34 VRHE) and neutral (-9.5 mA cm-2, 1.15% at 0.2 VRHE) conditions, surpassing CuO photocathodes by more than 3 and 3.3-times, respectively. Electrochemical studies suggested increased charge-carrier concentration, efficient charge-transfer, elongated lifetime of photogenerated electron owing to intimate contact between layers leading to internal electric field enhancement, charge separation. H2 production over CuO/CuxS photocathode was 80 µmol.cm-2.h-1, ηF=86%. DFT calculation underscores engineered CuO/CuxS substantially improves catalytic HER efficiency by tuning charge transfer, optimal ΔGH* at heterointerface. The study conveys principles applicable to various domains, facilitating the creation of vacancies in superior semiconducting materials for photo-electrocatalysts.