Enhanced light-driven hydrogen generation on carbon quantum dots with TiO2 nanoparticles. Issue 17 (23rd April 2021)

• Record Type: Journal Article
• Authors: Zhao, Fengjiao; Zhang, Feng; Han, Dongxue; Huang, Kai; Yang, Yang; Yin, Hongming
• Is Part Of: Physical chemistry chemical physics. Volume 23:Issue 17(2021)
• Page Start: 10448
• Page End: 10455
• Publication Date: 2021-04-23
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d1cp00417d
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : 77% enhanced light-driven H2 generation of CQDs with TiO2 nanoparticles by an efficient electron transfer to highly active redox band. Abstract : Solar to hydrogen (H2 ) conversion systems based on carbon nanomaterials have shown great potentials in the clean energy field recently. However, for most systems, energy level alignments and light-induced redox processes are still unclear, which hinder artificial designing for higher efficiency of solar energy conversion and further applications. Here we report 77% enhancement in the light-driven H2 generation efficiency of N, S co-doped carbon quantum dot (N, S-CQD) aqueous system by adding TiO2 nanoparticles. Using steady-state and transient spectroscopy, four specific energy levels of CQDs are confirmed with the band gaps of 3.55 eV (X4 ), 2.99 eV (X3 ), 2.76 eV (X2 ) and 1.75 eV (X1 ), respectively. The X2 energy band is highly active for H + reduction with a longer lifetime of 13.38 ns. Moreover, the observed low efficiency of intrinsic transition from X3 to X2 band of N, S-CQDs accounts for the poor performance of solar to H2 conversion for pure N, S-CQDs based on H2 generation and detailed time-resolved spectroscopic results. The mechanism of H2 generation enhancement can be explained by multiple electron transfer processes between N, S-CQDs and TiO2 NPs where TiO2 NPs act as electron intermediates that efficiently transfer electrons from the inert band (X3 ) to the active band (X2 ) for H2 generation. This study enriches the fundamental understanding of N, S-CQDs and provides a new pathway toward high-performance N, S-CQD-based solar to H2 conversion systems.