Time: 10：00a.m., 30th April.

Place: A718 SINANO

Nanostructured Electrocatalysts for Energy and Environmental Applications

Shuhui Sun

Institut National de la Recherche Scientifique (INRS), Center for Energy and Materials,

Montreal, Quebec, Canada

Email: shuhui@emt.inrs.ca; Personal website: http://www.inrs.ca/shuhui-sun?f=english

This talk will include two parts. Firstly, I will focus on our recent work on designing various novel Pt nanostructures as electrocatalysts for fuel cells. Over the past decade, great efforts have been devoted to developing proton exchange membrane (PEM) fuel cells that use hydrogen fuel and oxygen from the air to produce electricity with zero emission, for portable and automotive applications. Vehicle test data suggest that the U.S. Department of Energy (DOE) targets for hydrogen storage—a 250-mile range and a refueling time of less than 3 min—can be met with high-pressure hydrogen storage tanks. Now, the main challenge is the design of cheap and stable fuel cell catalysts. Among them, Pt, though very expensive, is the best catalyst and is hard to be replaced in a short term. It is well accepted that the activity and stability of Pt catalysts are highly dependent on their shape and size. Our strategy is to use nanotechnology to significantly increase the activity and durability of Pt-based catalysts through morphology, and size control. We have developed several advanced techniques, such as green chemistry and atomic layer deposition (ALD), to fabricate a series of novel nanostructured Pt catalysts, such as nanowires (NWs), nanotubes (NTs), sub-nanoclusters, and single atoms, etc. All these new types of catalysts exhibit much enhanced activity (up to 10 times) and stability (up to 6 times) compared to the commercially-used Pt/C nanoparticle catalysts, for fuel cells. [1-8] In addition, our recent progress on non-noble metal catalysts will also be reported.

In the second part, I will report our recent work on waste water treatment. Environmental pollution is a global menace, and its magnitude is increasing day-by-day due to urbanization, heavy industrialization and the changing lifestyles of people. The demand for hydrogen peroxide (H2O2) is booming since it is considered as one of the most environmentally friendly and versatile chemical oxidants available and has a wide range of applications, especially in waste water treatment (degradation of organic pollutants). In-situ generation of H2O2 has attracted a growing interest since it avoids the cost and risks involved in the transportation and handling of concentrated H2O2. We developed a simple method to prepare two types of catalysts: Fe3O4/Printex and Fe3O4/graphene, which show promising activity for ORR in alkaline medium to generate H2O2. Further, both catalysts show excellent durability. These catalysts hold very promising potential applications in waste water treatment.

References:

(1) S. H. Sun et al, Angew. Chem. Int. Ed., 50, 422 (2011). (VIP+ Cover); (2) S. H. Sun et al, Adv. Mater., 20, 571 (2008); (3) S. H. Sun et al, Adv. Mater., 20, 3900 (2008). (4) G. Zhang et al, Scientific Reports, (2013), 3: 526. (5)S. Du et al, Scientific Reports, (2014). 4, 6439; (6) S. H. Sun et al, Chemistry-A European Journal, 16, 829 (2010). (Inside Cover); (7) S. H. Sun et al, Chem. Mater., 19, 6376 (2008); (8) S. H. Sun et al, Chem. Commun., 45, 7048 (2009); (9) W. Barros et al, Electrochimica Acta, (2015), In press.