Green Light Photoelectrocatalysis with Sulfur-Doped Carbon Nitride: Using Triazole-Purpald for Enhanced Benzylamine Oxidation and Oxygen Evolution Reactions

30 August 2022, Version 1


Novel high performing materials will dictate the pace of reinventing industrial chemical processes to attain desired carbon neutrality targets. Regarding the urgency of exploiting solar irradiation long range visible-light photoelectrocatalysts from abundant resources will play a key role in the aforementioned effort. Anionic doping via co-polymerization and pre-organization of precursors results in tuneable and extrinsic semiconductors, making this a highly attractive methodology. Triazole derivative-purpald, an unexplored precursor but sulfur (S) container, combined with melamine during one solid-state polycondensation reaction with two thermal steps leads to S-doped carbon nitrides (C3N4). The series of S-doped/C3N4-based materials demonstrated enhanced optical, electronic, structural, geometric, textural, and morphological properties and exhibited higher performance in organic benzylamine photooxidation, oxygen evolution, and similar storing energy (capacitor brief investigation) than references. Among the five composites, 50M-50P exhibited the highest photooxidation conversion yield (84±3%) of benzylamine to imine at 535 nm – green light for 48h, due to an extra discrete shoulder reaching ~700 nm, an unusual high sulfur content, preservation of crystal size, new intraband energy states, rare deep structural defects by layer distortion, hydrophobic surface, low porosity, and 10-16 nm pores. An in-depth analysis of S doping was investigated coupling x-ray photoelectron spectroscopy, transmission electron microscope, and elemental analysis, providing insights on bonds, distribution, and surface/bulk content. This work contributes to the development of amorphous photocatalysts with long-visible-light range for solar energy conversion and storage.


carbon nitride

Supplementary materials

Electronic supplementary information
Figure S1. TGA decomposition profiles of purpald and melamine precursors. Figure S2. TGA and MS ion current curves for C3N4(P). Figure S3. SEM images. Figure S4. Fitting of the XRD patterns. Figure S5. FTIR-ATR spectra. Figure S6. Emission spectra of the LED Green lamp for photooxidation. Figure S7. EPR spectra upon 365 nm irradiation and in dark of C3N4 50M-50P in a) DMPO and b) TEMP. Figure S8. Emission spectra of the LED White lamp, λ365nm used for PEC measurements. Figure S9. LSV curves in dark conditions. Figure S10. EDS mapping analysis of C3N4(P) . Figure S11. EDS spectra of C3N4(P). Figure S12. Bright/dark field and HRTEM images. Figure S13. XPS C and N spectra. Figure S14. UPS spectra including the fitting. Figure S15. Gas chromatography calibration curve using dibenzylimine standard. Table S1. Optical and electronic properties. Table S2. Elemental analysis results. Table S3. State-of-the-art OER photoelectrocatalyst.


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