title: Graphene-Draped Semiconductors for Enhanced Photocorrosion Resistance and Photocatalytic Properties.
abstract: Semiconductor photocatalysts have been widely used for photochemical water splitting, purification of organic contaminants, and bacterial detoxification. However, most photocatalysts suffer greatly from photocorrosion under visible-light irradiation. Here we report a viable strategy to markedly improve photocorrosion resistance of photocatalysts by draping ultrathin yet highly impermeable graphene layers over a semiconductor CdS electrode. Remarkably, the average lifetime of three-layer-graphene-draped CdS photocatalyst is prolonged by 8 times compared to the as-prepared CdS counterpart without graphene draping. The introduction of graphene layers largely suppresses the charge carrier recombination of the CdS film and decreases the carrier transfer resistance at the graphene-draped CdS electrode/electrolyte interface, as revealed by the photoluminescence (PL) and electrochemical impedance spectroscopy studies, respectively, thereby leading to increased photocurrent and enhanced photocatalytic performance (i.e., a 2.5-fold increase in comparison to that in as-prepared CdS case). Our density functional theory calculations also show that electrons are readily transferred from CdS to graphene, correlating well with the PL measurement. The photocorrosion is mainly caused by oxidation reaction between CdS and O2and H2O assisted with photogenerated holes, evidenced by X-ray photoelectron spectroscopy characterization. The draped graphene effectively prevents the direct contact between the CdS film and O2and H2O, thus considerably retarding the photocorrosion of CdS upon visible-light exposure. This simple yet robust graphene-draping strategy for antiphotocorrosion of semiconductor photocatalysts is environmentally friendly as it prevents them from entering into the surrounding environment, thus eliminating the possible secondary pollution.
authors.affiliation: Department of Applied Physics and ‡Institute of Textiles & Clothing, The Hong Kong Polytechnic University , Hung Hom, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Mengye
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Applied Physics and ‡Institute of Textiles & Clothing, The Hong Kong Polytechnic University , Hung Hom, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Lejuan
authors.initials: L
authors.lastname: Cai
authors.affiliation: Department of Applied Physics and ‡Institute of Textiles & Clothing, The Hong Kong Polytechnic University , Hung Hom, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Applied Physics and ‡Institute of Textiles & Clothing, The Hong Kong Polytechnic University , Hung Hom, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Feichi
authors.initials: F
authors.lastname: Zhou
authors.affiliation: Department of Applied Physics and ‡Institute of Textiles & Clothing, The Hong Kong Polytechnic University , Hung Hom, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Kang
authors.initials: K
authors.lastname: Xu
authors.affiliation: Department of Applied Physics and ‡Institute of Textiles & Clothing, The Hong Kong Polytechnic University , Hung Hom, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Tao
authors.affiliation: Department of Applied Physics and ‡Institute of Textiles & Clothing, The Hong Kong Polytechnic University , Hung Hom, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Yang
authors.identifier: 0000-0002-8943-0861
authors.initials: Y
authors.lastname: Chai