英国College London大学Junwang Tang教授来访

报告题目：Rational design of photocatalysts for water splitting and CO₂conversion

报告人：Prof.Junwang Tang(Department of Chemical Engineering, University College London, UK)

报告时间：3月31日（星期四）上午10：00

报告地点：物理科技楼101

报告摘要：

CO₂concentration in the atmosphere reached its record (400ppm) this year, which causes a serious concern about catastrophic climate change and global warming. The major contributor is by far the combustion of fossil fuel. There are two potential solutions to solve the problem. One is to replace fossil fuel by renewable energy and the other is to help nature maintain the carbon cycle by artificial conversion of CO₂.

As the most abundant renewable energy source available on the Earth, solar energy has the potential to meet the increasing global energy demands. Therefore solar energy conversion and storage, via water splitting has been attracting substantial interest over the last ten years, which can provide renewable H2 fuel with a strong potential to replace fossil fuel. In parallel, CO₂photoreduction by sunlight has also drawn increasing attention, which can not only provide a renewable fuel but also dramatcially reduce CO₂emission, thus facilitating carbon cycle.

The key in these technologies is an efficient photocatalyst which can convert a photon to a pair of charge carriers and then utilise them to drive the expected chemical reactions. The current low efficiency in these processes is contributed to fast charge recombination in an inorganic semiconductor.¹In this talk, carbon-based photocatalysts, e.g C₃N₄, covalent triazine etc will be presented and their excellent performance for both water splitting and CO₂conversion will be discussed. The reaction mechanism behind their novel properties will also be pointed out.

Stimulated by our recent research outcomes on the charge dynamics in inorganic semiconductor photocatalysts,¹we developed novel materials for solar driven hydrogen synthesis and CO₂reduction. The first example is pure water splitting for simultaneous H₂and O₂evolution by C3N4 semiconductor based system in a suspensions solution under visible light (Figure 1).^2,3In parallel a few junction structures for CO₂photoreduction under visible light irradiation have been developed. For example, Figure 2 shows CO₂reduction by a junction composed of C₃N₄and the major product is methanol instead of CO. More recently, covalent triazine photocatalysts exhibit excellent water oxidation ability, active from UV till IR when using silver ions as electron scavenger apart from its activity for H₂production from water. This is to our knowledge the first photocatalyst showing such a wide operation window for water oxidation which is the rate-determined step in solar driven water splitting. These novel properties were attributed to efficient charge separation by a junction and good charge transport pathway in these photocataysts, which were evidenced by diverse spectroscopies, elementary analysis and theoretical modelling.

References

1.J. Tang, J. R. Durrant and D. R Klug, J. Am. Chem. Soc.,130(42) (2008)13885-13891.

2.D. J.Martin, K. Qiu, S. A Shevlin, A.D. Handoko, X. Chen, Z, Guo, and J. Tang, Angewandte Chemie-International Edition,53 (35) (2014)9240-9245.

3.D.J. Martin,P. J. T. Reardon,S. J. A.Moniz, andJ. Tang,,J. Am. Chem. Soc.136(2014)12568.Highlighted inChemical & Engineer Newson Sep. 10, 2014.

4.D. Kong, S. A. Shevlin, Z. Guo, andJ. Tang.Submitted.

报告人简介：

Dr Junwang Tangis a Reader in Energy in the Department of Chemical Engineering at UCL anda Fellow of the RSC.Hereceived his PhD in Physical Chemistry in 2001. His research interests encompass structure-controlled nanomaterials synthesis by a flow system powered by microwave irradiation, solar H₂synthesis from water, CO₂capture and conversion to a renewable fuel, methane conversion, photocatalytic environmental purification and microwave catalysis. Such studies are undertaken in parallel with the mechanistic understanding and device optimisation to address the renewable energy supply and environmental purification, resulting into>100 papers with >5500 citations, 10 patents and many invited lectures over the last several years. He is an Editor-in-Chief of Journal of Advanced Chemical Engineering, the guest Editor-in-Chief of the International Journal of Photoenergy, 2012, Associate Editor of Chin J. Catalysis and Asia-Pacific J. Chemical Engineering. He also sits on the editorial board of several international journals. He is the Vice President of the Chinese Society of Chemical Science and Technology in the UK, Honorary Lecturer at Imperial College London, Adjunct Professor in Nanjing Tech University and Chinese Academy of Sciences.