Experimental Identification of Ultrafast Reverse Hole Transfer at the Interface of the Photoexcited Methanol/Graphitic Carbon Nitride System

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Abstract
An experimental scrutiny of the photoexcited hole dynamics in a prototypical system is presented in which hole‐scavenging methanol molecules are chemisorbed on a graphitic carbon nitride (g‐C3N4) substrate. A set of comparison and control experiments by means of femtosecond time‐resolved transient absorption (fs‐TA) spectroscopy were conducted. The elusive reverse hole transfer (RHT) process was identified, which occurs on a timescale of a few hundred picoseconds. The critical role of interfacially chemisorbed methoxy (instead of methanol) as the dominant species responsible for hole scavenging was confirmed by a control experiment using protonated g‐C3N4 as the substrate. A hot‐hole transfer effect was revealed by implementing different interband photoexcitation scenarios. The RHT rate is the key factor governing the hole‐scavenging ability of different hole scavengers.
Funding Information
  • Ministry of Science and Technology of the People's Republic of China (2016YFA0200602, 2017YFA0303500)
  • National Natural Science Foundation of China (21573211, 21633007, 21421063, 21790350)
  • Chinese Academy of Sciences (2016HSC-IU003)

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