Chemistry, Light and Dynamics Seminar

08 November 2021, 3:00 pm–4:00 pm

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Structure-photophysics-activity relationships in carbon nitride photocatalysts and their heterojunctions

This event is free.

Event Information

Open to

UCL staff | UCL students






CLD committee


Ramsay Lecture Theatre
Christopher Ingold Building
20 Gordon St

Polymeric photocatalysts made of Earth-abundant elements have been extensively developed over the past decade to take advantage of their synthetic tunability.1 Within this family, carbon nitrides (CNx)2 are emerging as exciting photocatalysts because of their high photocatalytic performance combined with good stability and facile synthesis. However, there still remains significant gaps in our knowledge of the photophysical properties of these organic polymeric materials, severely impeding rational optimization. Determining the pathways and mechanism of photoinduced processes such as charge generation/separation and interfacial redox reaction will greatly aid our efforts to engineer better CNx photocatalysts. We have investigated the structure-activity-photophysics relationships in CNx with controlled morphological changes. We observe different surface area/activity trends based on the synthetic route that was taken, suggesting that the electronic properties of the materials can be influenced by morphology under certain cases.

Another material of interest is carbon nanodots (CDs). These nanoparticles are easily prepared by carbonisation of small molecule precursors and can be deposited on the surface of CNx to form heterojunctions. We’ve reported intriguing behaviour at CNx/CD heterojunctions where the flow of charges is dependant on the type of CDs used.3 Segregation of opposite charges across the two different materials leads to impressive nearly quantitative (~ 99.6%) chemical selectivity for the production of methanol from CO2 reduction, oxidizing only water. By replacing CNx with a related polymer that incorporates O linker groups, benchmark apparent quantum yield of 5.9% (420 nm) for methanol production from CO2, again without any sacrificial electron donors.4

We are taking the next step to develop a full picture of the charge carrier dynamics by expanding our spectroscopic capabilities to transient absorption microscopy (TAM). Notably, our first-of-its-kind TAM system monitors the microsecond – second timescales relevant to the complex multi electron redox reactions that occur to produce solar fuels. Spatial mapping of the charge carrier dynamics on the micron scale provides novel insights into the heterogeneity in CNx films. The identification of ‘hot spots’ with favorable charge carrier dynamics can push the field into uncovering the optimal structure and local environment in defect-rich organic semiconductors such as CNx.

(1)          Wang, Y.; Vogel, A.; Sachs, M.; Sprick, R. S.; Wilbraham, L.; Moniz, S. J. A.; Godin, R.; Zwijnenburg, M. A.; Durrant, J. R.; Cooper, A. I.; Tang, J. Nat. Energy 2019, 4 (9), 746–760.

(2)          Wang, X.; Maeda, K.; Thomas, A.; Takanabe, K.; Xin, G.; Carlsson, J. M.; Domen, K.; Antonietti, M. Nat. Mater. 2009, 8 (1), 76–80.

(3)          Wang, Y.; Liu, X.; Han, X.; Godin, R.; Chen, J.; Zhou, W.; Jiang, C.; Thompson, J. F.; Mustafa, K. B.; Shevlin, S. A.; Durrant, J. R.; Guo, Z.; Tang, J. Nat. Commun. 2020, 11 (1), 2531.

(4)          Wang, Y.; Godin, R.; Durrant, J. R.; Tang, J. Angew. Chem. Int. Ed. 2021, 60 (38), 20811–20816.

About the Speaker

Dr. Robert Godin

at Department of Chemistry, The University of British Columbia, Kelowna, BC, Canada