Ni-foam supported Co(OH)F and Co–P nanoarrays for energy-efficient hydrogen production via urea electrolysis

Author(s): Min Song ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Zijin Zhang ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Qingwei Li ⁶ ^, ⁷ ^, ⁸ ^, ⁵ , Wei Jin ⁹ ^, ¹⁰ ^, ¹¹ ^, ⁵ , Zexing Wu ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Gengtao Fu ¹² ^, ¹³ ^, ¹⁴ ^, ¹⁴ , Xien Liu ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵

Publication date (Electronic): 2019

Journal: Journal of Materials Chemistry A

Publisher: Royal Society of Chemistry (RSC)

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Abstract

Ni-foam-supported Co(OH)F and Co–P nanoarrays were developed for energy-efficient hydrogen production with the assistance of urea electrolysis.

Abstract

It is an urgent requirement to develop non-precious metal-based catalysts with excellent electrocatalytic activity and stability to accelerate the development of hydrogen generation via energy-efficient routes. Herein, a facile and scalable strategy was developed to synthesize both rod-like Co(OH)F and Co–P nanoarrays supported on Ni-foam, denoted as Co(OH)F/NF and Co–P/NF, respectively. Electrochemical measurements demonstrate that Co–P/NF exhibits excellent electrocatalytic performance for the hydrogen evolution reaction (HER), delivering a low overpotential of 70 mV and 43 mV at 10 mA cm ⁻² in alkaline and acid media, respectively. Furthermore, the as-prepared Co(OH)F/NF contributes to an outstanding oxygen evolution reaction (OER) performance with a low oxidation potential of about 1.5 V at 10 mA cm ⁻². In addition, the Co(OH)F/NF also can enable highly efficient urea oxidation reaction (UOR) electrocatalysis, which can be utilized to substitute OER to lower the overpotential and thus reduce electrical energy consumption during H ₂-production. As a proof of concept, full water-splitting measurements were performed with Co–P/NF and Co(OH)F/NF as cathode and anode, respectively, in 1 M KOH with 0.7 M urea. The Co–P/NF‖Co(OH)F/NF electrode is capable of producing a current density of 20 mA cm ⁻² at a cell potential of only 1.42 V, which is 230 mV less than that for the urea-free counterpart, demonstrating its potential feasibility in practical applications of energy-efficient hydrogen production.