title: Highly efficient photocatalytic H₂ evolution from water using visible light and structure-controlled graphitic carbon nitride.
abstract: The major challenge of photocatalytic water splitting, the prototypical reaction for the direct production of hydrogen by using solar energy, is to develop low-cost yet highly efficient and stable semiconductor photocatalysts. Herein, an effective strategy for synthesizing extremely active graphitic carbon nitride (g-C3N4) from a low-cost precursor, urea, is reported. The g-C3N4 exhibits an extraordinary hydrogen-evolution rate (ca. 20,000 μmol h(-1) g(-1) under full arc), which leads to a high turnover number (TON) of over 641 after 6 h. The reaction proceeds for more than 30 h without activity loss and results in an internal quantum yield of 26.5% under visible light, which is nearly an order of magnitude higher than that observed for any other existing g-C3N4 photocatalysts. Furthermore, it was found by experimental analysis and DFT calculations that as the degree of polymerization increases and the proton concentration decreases, the hydrogen-evolution rate is significantly enhanced.
authors.affiliation: Solar Energy Group, Department of Chemical Engineering, UCL, Torrington Place, London, WC1E 7JE (UK).
authors.forename: David James
authors.initials: DJ
authors.lastname: Martin
authors.forename: Kaipei
authors.initials: K
authors.lastname: Qiu
authors.forename: Stephen Andrew
authors.initials: SA
authors.lastname: Shevlin
authors.forename: Albertus Denny
authors.initials: AD
authors.lastname: Handoko
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Chen
authors.forename: Zhengxiao
authors.initials: Z
authors.lastname: Guo
authors.forename: Junwang
authors.initials: J
authors.lastname: Tang
keywords: graphitic carbon nitride; hydrogen production; polymerization; protonation; water splitting