Platinum Nanowire Based Electrodes with Boosted Catalyst Utilization for Efficient Hydrogen Production in PEM Electrolyzer Cells

Abstract

Due to the limited triple phase boundary (TPB) sites caused by the intrinsically low electrochemical active surface area (ECSA) of catalysts and poor interfacial contact between a catalyst layer and a porous transport layer, high noble metal catalyst loadings are generally required to achieve high-efficiency hydrogen production in low-temperature proton exchange membrane electrolyzer cells (PEMECs). Our recent studies have demonstrated that direct deposition of platinum nanoparticles onto 25-µm-thick titanium liquid/gas diffusion layers (LGDLs) can significantly reduce the cathode catalyst waste.1-3 To further lower the cost of both catalysts and electrode fabrication, for the first time, we develop a green chemical synthesis approach at room temperature to fabricate ultrathin electrodes composed of platinum nanowires (PtNW) in-situ grown on thin titanium LGDLs.4 Our developed high-speed micro-scale visualization system reveals that ultrathin Pt nanowires display more uniform reaction sites and favorable bubble detachment compared to conventional Pt nanoparticles. Impressively, when integrated into a PEMEC, the PtNW electrode with a low catalyst loading of 0.2 mg cm−2 can achieve a low cell voltage of 1.643 V and high efficiency of 90.08% at 1000 mA cm−2, which significantly surpasses conventional electrodes with high loadings. Such performance enhancement is mainly attributed to the high ECSA of catalysts, favorable hydrogen bubble detachment, and good conductivity of the whole electrode. References Z.Y. Kang, G.Q. Yang, J.K. Mo, Y.F. Li, S.L.Yu, D.A. Cullen, S.T. Retterer, T.J. Toops, G. Bender, B.S. Pivovar, J.B. Green Jr, and F.Y. Zhang. "Novel thin/tunable gas diffusion electrodes with ultra-low catalyst loading for hydrogen evolution reactions in proton exchange membrane electrolyzer cells." Nano Energy. 47, 434-441 (2018).J.K. Mo, Z.Y. Kang, S.T. Retterer, D.A. Cullen, T.J. Toops, J.B. Green Jr, M.M. Mench, and F.Y. Zhang. “Discovery of true electrochemical reactions for ultrahigh catalyst mass activity in water splitting.” Science Advances, 2, 1600690 (2016).Z.Y. Kang, J.K. Mo, G.Q. Yang, S.T. Retterer, D.A. Cullen, T.J. Toops, J.B. Green Jr, M.M. Mench, and F.Y. Zhang. “Investigation of thin/well-tunable liquid/gas diffusion layers exhibiting superior multifunctional performance in low-temperature electrolytic water splitting.” Energy & Environmental Science, 10, 166-175 (2017).Z.Q. Xie, S.L. Yu, G.Q. Yang, K. Li, L. Ding, W.T. Wang, D.A. Cullen, H.M. Meyer III, S.T. Retterer, Z.L. Wu, P.X. Gao and F.Y. Zhang. "Ultrathin platinum nanowire based electrodes for high-efficiency hydrogen generation in practical electrolyzer cells." Chemical Engineering Journal. 410, 128333 (2021).