Highly Efficient and Stable Photoelectrochemical Hydrogen Evolution with 2D-NbS2/Si Nanowire Heterojunction.

In recent days, 2-dimensional (2D) niobium disulfide (NbS2) with near-zero Gibbs free energy and superlative acid electrolyte stability has provoked a great deal of interest toward hydrogen evolution reaction (HER) electrocatalyst due to its active basal and edge sulfur sites. Herein, we developed a single step method for the direct deposition of 2D-NbS2 on high-aspect-ratio topographies of silicon nanowires (NWs) by chemical vapor deposition for the applications in HER electrocatalyst. The resultant 2D-NbS2 electrocatalyst demonstrates the HER overpotential of ∼74 mV vs RHE (reversible hydrogen electrode) @ 1 mA/cm2 under acidic conditions and stable for more than 20 h. More importantly, we developed the Si NWs array based photoelectrochemical water-splitting system with the direct deposition of 2D-NbS2 as HER catalyst. The resultant 2D-NbS2-Si NWs photocathode system demonstrates improved charge transfer characteristics at the Si-NbS2 interfaces that leads to an enhanced turn on potential (from 0.06 to 0.34 V vs RHE) with the current density of -28 mA/cm2 at the 0 V vs RHE. The results evidence the synergistic effect of 2D-NbS2 electrocatalysts that addresses poor surface kinetics of Si toward solar water electrolysis. Our comprehensive studies reveal NbS2 as a new class of photoelectrochemical cocatalyst for efficient solar HER performance by promoting the charge transfer process with prolonged acid stability.

Gnanasekar, P., Periyanagounder, D., Varadhan, P., He, J.-H., & Kulandaivel, J. (2019). Highly Efficient and Stable Photoelectrochemical Hydrogen Evolution with 2D-NbS2/Si Nanowire Heterojunction. ACS Applied Materials & Interfaces. doi:10.1021/acsami.9b14713

K.J. thanks the Department of Science and Technology (DST), Govt. of India for the financial support to develop the infrastructural facility under the scheme of FIST and Nanomission (Contract No. SR/NM/NS-1502/2014). K.J. also acknowledges Ministry of Human Resource Development under Rashtriya Uchchatar Shiksha Abhiyan (RUSA), Alexander von Humboldt (AvH) partial instrumentational support. G.P. acknowledges DST-INSPIRE, Govt. of India for the award of Junior Research Fellowship (DST INSPIRE-JRFIF#170198 DST/INSPIRE Fellowship/2016).

American Chemical Society (ACS)

ACS applied materials & interfaces


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