In-situ grown nanoscale p-n heterojuction of Cu2S-TiO2 thin film for efficient photoelectrocatalytic H2 evolution

Abstract

Nanoscale heterojuction thin film of Cu2S-TiO2 has been grown by sol-gel technique and has been employed for efficient H2 production through water splitting. This nanoscale heterojunction has been grown in three steps which include ion conducting Li4Ti5O12 thin film deposition and ion-exchange (Li+↔Cu+) followed by a sulfurization process. To study the photoelectrochemical performance of this Cu2S-TiO2 heterojunction thin film, photoanodes were fabricated on TiO2 coated FTO substrate. The TiO2 film was deposited by two different methods - the sol-gel method and colloidal TiO2 nanoparticles (TiO2–NP). Highest photocurrent of ∼36 mAcm−2 was obtained by Cu2S-TiO2/TiO2–NP/FTO photoanode under 0.5 V potential (E Vs. RHE, 1 M KOH). The photocurrent is ∼103 times higher compared to that of the bare TiO2 photoanode and stable for several hours. The photoelectrochemical (PEC) behavior is much higher with respect to previous reports on Cu2S (NP)-TiO2 nanocomposite photoanodes, which is due to the significant reduction in carrier recombination at the electronically coupled Cu2S-TiO2 heterojunction interface.