Controlled Synthesis of Nitro-Terminated Poly[2-(3-thienyl)-ethanol]/g-C3N4 Nanosheet Heterojunctions for Efficient Visible-Light Photocatalytic Hydrogen Evolution

Exploration of closely contacted polymeric nanoheterojunctions with suitable frontier molecular orbital energy levels is highly desired for promoting the carrier separation and further improving the photocatalytic performance. In our work, poly[2-(3-thienyl)ethanol]/g-C3N4 (PTEtOH/g-C3N4) nanosheet heterojunctions were successfully fabricated using a controlled surface hydroxyl-induced assembly process and displayed obviously improved visible-light performance for H-2 evolution. As verified by time-resolved photoluminescence spectra, surface photovoltage spectra and center dot OH amount measurements, the improved performance is due to the promoted photo-generated carrier transfer and separation in the synthesized PTEtOH/g-C3N4 heterojunction with strengthened interface contacts via hydrogen bonding. Furthermore, single-wavelength photocurrent action spectra were performed to confirm that the promoted photogenerated carrier separation is mainly dependent on the excited high-level electron transfer from g-C3N4 to PTEtOH. Interestingly, the photocatalytic performance is further improved by synthesizing nitro-terminated PTEtOH (N-PTEtOH) with lowered LUMO energy level and decreased particle size and then constructing N-PTEtOH/g-C3N4 nanosheet heterojunction, exhibiting a factor-of-15 enhancement, in comparison with that of g-C3N4 and obvious superiority to reported photoactivities. Noteworthily, abundant hydroxyl groups on the surface of the heterojunctions are beneficial for the uniform deposition of Pt nanoparticles as co-catalysts and hence for photocatalytic reactions. This study offers a feasible strategy to design efficient polymeric heterojunctions as nanophotocatalysts for solar-lightdriven energy production.

Automated summary

The study successfully fabricated PTEtOH/g-C3N4 nanosheet heterojunctions with suitable energy levels to promote carrier separation and improve photocatalytic performance. Enhanced performance was attributed to promoted carrier transfer and separation in the synthesized heterojunction with strengthened interface contacts via hydrogen bonding. Additionally, the photocatalytic performance was further improved by synthesizing N-PTEtOH with lowered energy levels and constructing N-PTEtOH/g-C3N4 nanosheet heterojunction, exhibiting a significant enhancement in comparison with g-C3N4.