In situ protonated-phosphorus interstitial doping induces long-lived shallow charge trapping in porous C3−xN4 photocatalysts for highly efficient H2 generation. Issue 2 (14th December 2022)

• Record Type: Journal Article
• Authors: Wang, Wenchao; Du, Lili; Xia, Ruiqin; Liang, Runhui; Zhou, Tao; Lee, Hung Kay; Yan, Zhiping; Luo, Hao; Shang, Congxiao; Phillips, David Lee; Guo, Zhengxiao
• Is Part Of: Energy & environmental science. Volume 16:Issue 2(2023)
• Page Start: 460
• Page End: 472
• Publication Date: 2022-12-14
• Subjects: Energy conversion -- Periodicals; Fuel switching -- Periodicals; Environmental sciences -- Periodicals; Environmental chemistry -- Periodicals; 333.79
• DOI: 10.1039/d2ee02680e
• Languages: English
• ISSNs: 1754-5692

Abstract

Abstract : Efficient photocatalytic solar-to-H2 conversion is pivotal to zero-carbon energy supply. Abstract : Efficient photocatalytic solar-to-H2 conversion is pivotal to zero-carbon energy supply. Graphitic carbon nitride (g-C3 N4 ) is a promising visible-light photocatalyst but suffers from intrinsic electron–hole recombination and deep-charge trapping, limiting its efficiency. Here, we show a synergistic strategy of porosity, vacancy and shallow(trapping)-state engineering to enrich catalytic sites and promote the lifetime of active electrons by thermochemical treatment and phosphorus-interstitial-doping. The latter enhances the electron delocalization in the π-conjugate polymeric structure. The optimized photocatalyst shows a ∼800% increase in H2 generation (6323 μmol h −1 g −1 ) and an about 5-fold increase in quantum efficiency (QE420 nm = 5.08%). The superior performance is attributed to the long-lived shallow charge trapping, as a result of proton-feeding to the coordinated phosphorus site during the photocatalytic reaction, which enhances the photogenerated carrier lifetime and positively optimizes the band structure of the catalyst. Femtosecond transient absorption spectroscopy reveals a doubling lifetime of shallow-trapped charges (∼405.5 ps), favoring high mobility for electron-involved photocatalytic H2 generation. This work provides a new mechanism for improving charge carrier dynamics and photocatalytic performance.