Superaerophobic CoP Nanowire Arrays as a Highly Effective Anode Electrocatalyst for Direct Hydrazine Fuel Cells

• Published in: ACS applied energy materials 2022-08, Vol.5 (8), p.9455-9462
• Main Authors: Sun, Haoran, Gao, Liyao, Kumar, Anuj, Cao, Zibo, Chang, Zheng, Liu, Wen, Sun, Xiaoming
• Format: Article
• Language: English
• ISSN: 2574-0962; 2574-0962
• DOI: 10.1021/acsaem.2c01005

One of the major challenges in developing direct hydrazine fuel cells (DHzFCs) is the creation of highly efficient, robust, and inexpensive electrocatalysts with a superaerophobic property for the hydrazine oxidation reaction (HzOR). Herein, a cobalt phosphide nanowire array (CoP-NWA@CP) is grown on a carbon paper substrate as a highly efficient electrocatalyst for the HzOR in alkaline medium, which features a superaerophobic surface that is highly antigaseous and conducive to nitrogen evolution (a gaseous byproduct of the HzOR). The catalyst demonstrates a significant HzOR performance with an onset potential of −61 mV (vs RHE), an ultralow overpotential of −32 mV@10 mA cm–2, and superior stability with little current density loss over 10,000 s at an overpotential of 0.42 V (vs RHE). The remarkable HzOR performance of the CoP-NWA@CP catalyst is attributed not only to its high intrinsic activity but also to its nanowire array design, which offers a large specific surface area and rapid electron and mass transfer, as well as its superaerophobic surface wettability to expedite the release of N2 from the catalyst surface. Furthermore, a DHzFC is constructed using the CoP-NWA@CP catalyst as the anode and commercial MnO2 as the cathode, which delivers a high open-circuit voltage of 0.905 V, a remarkable power density of 300 mW cm–2, and 95% retention after 12.5 h operation, suggesting great potential of CoP-NWA@CP in practical applications.