Photo-Electro Catalytic Hydrogen Generation using Graphene-hBN Atomic Stacks

 

Sumit Bawari, Nisheal M. Kaley, Sourav Pal, Jagannath Mondal, and T. N. Narayanan 

Tata Institute of Fundamental Research - Hyderabad

E-mail id: sumitb[at]tifrh.res.in, jmondal[at]tifrh.res.in, tnn[at]tifrh.res.in

 

Abstract

vdW stacked heterostructures are a new and interesting aspect in 2D materials, where stacking can induce meta properties. In this work, we study stacked heterostructures of graphene and hBN, whereupon hydrogen evolution reaction (HER) is studied. Hydrogen is a promising energy source for fuel cells, and electrochemical HER is a carbon neutral method to obtain pure hydrogen. The main bottleneck in creating this hydrogen economy is that precious metals such as platinum are benchmark catalysts. Thus new economically feasible materials need to be found. Through experiments and computational methods spanning electronic levels, bond energies, and ion dynamics, we study G/hBN heterostructures. Experimentally, we find that vdW heterostructures of G/hBN and hBN/G exhibit enhanced HER activity. This enhanced activity is studied through Molecular Dynamics (MD) simulations and Density Functional Theory (DFT) based calculations, which provide insight into sorption behaviour and charge transfer efficiency respectively, for efficient catalysis. Using both methods, we identify the catalytically active sites on the G/hBN interface and try to justify the experimental observations. The electronic structure of G/hBN stacks has also been a topic of much study. hBN stacked on graphene opens up a small band gap in graphene, and mid state visible range transition has also been suggested by a recent study. Through DFT, we reproduce results that suggest the formation of interlayer excitons between graphene and hBN. Light enhanced electrochemical studies and UV-Vis absorption spectra shows visible light absorption in different G- hBN heterostructures experimentally.

 

References:

 

1.      Atomistic Elucidation of Sorption Processes in Hydrogen Evolution Reaction on a van der Waals C 122 (18), pp 10034-10041 (2018).

2.      On the Hydrogen Evolution Reaction Activity of Graphene-hBN van der Waals Heterostructures, Sumit.

3.      Graphene-hBN van der Waals Heterostructures for Photo-Electrocatalytic Hydrogen Generation (in preparation).