Heterostructured Core-Shell Ni-Co@Fe-Co Nanoboxes of Prussian Blue Analogues for Efficient Electrocatalytic Hydrogen Evolution from Alkaline Seawater

Hao Zhang; Jiefeng Diao; Mengzheng Ouyang; Hossein Yadegari; Mingxuan Mao; Mengnan Wang; Graeme Henkelman; Fang Xie; D Jason Riley

doi:10.1021/acscatal.2c05433

Heterostructured Core-Shell Ni-Co@Fe-Co Nanoboxes of Prussian Blue Analogues for Efficient Electrocatalytic Hydrogen Evolution from Alkaline Seawater

ACS Catal. 2023 Jan 9;13(2):1349-1358. doi: 10.1021/acscatal.2c05433. eCollection 2023 Jan 20.

Authors

Hao Zhang¹, Jiefeng Diao², Mengzheng Ouyang³, Hossein Yadegari¹, Mingxuan Mao⁴, Mengnan Wang¹, Graeme Henkelman², Fang Xie¹, D Jason Riley¹

Affiliations

¹ Department of Materials and London Center for Nanotechnology, Imperial College London, London SW7 2AZ, U.K.
² Department of Chemistry and the Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas 78712 United States.
³ Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ U.K.
⁴ Department of Electrical and Electronic Engineering, Imperial College London, London SW7 2AZ U.K.

Abstract

The rational construction of efficient and low-cost electrocatalysts for the hydrogen evolution reaction (HER) is critical to seawater electrolysis. Herein, trimetallic heterostructured core-shell nanoboxes based on Prussian blue analogues (Ni-Co@Fe-Co PBA) were synthesized using an iterative coprecipitation strategy. The same coprecipitation procedure was used for the preparation of the PBA core and shell, with the synthesis of the shell involving chemical etching during the introduction of ferrous ions. Due to its unique structure and composition, the optimized trimetallic Ni-Co@Fe-Co PBA possesses more active interfacial sites and a high specific surface area. As a result, the developed Ni-Co@Fe-Co PBA electrocatalyst exhibits remarkable electrocatalytic HER performance with small overpotentials of 43 and 183 mV to drive a current density of 10 mA cm^-2 in alkaline freshwater and simulated seawater, respectively. Operando Raman spectroscopy demonstrates the evolution of Co²⁺ from Co³⁺ in the catalyst during HER. Density functional theory simulations reveal that the H*-N adsorption sites lower the barrier energy of the rate-limiting step, and the introduced Fe species improve the electron mobility of Ni-Co@Fe-Co PBA. The charge transfer at the core-shell interface leads to the generation of H* intermediates, thereby enhancing the HER activity. By pairing this HER catalyst (Ni-Co@Fe-Co PBA) with another core-shell PBA OER catalyst (NiCo@A-NiCo-PBA-AA) reported by our group, the fabricated two-electrode electrolyzer was found to achieve high output current densities of 44 and 30 mA cm^-2 at a low voltage of 1.6 V in alkaline freshwater and simulated seawater, respectively, exhibiting remarkable durability over a 100 h test.