A hierarchically porous nickel-copper phosphide nano-foam for efficient electrochemical splitting of water

Li Wei; Kunli Goh; Özgür Birer; H Enis Karahan; Jian Chang; Shengli Zhai; Xuncai Chen; Yuan Chen

doi:10.1039/c6nr09864a

A hierarchically porous nickel-copper phosphide nano-foam for efficient electrochemical splitting of water

Nanoscale. 2017 Mar 30;9(13):4401-4408. doi: 10.1039/c6nr09864a.

Authors

Li Wei¹, Kunli Goh², Özgür Birer³, H Enis Karahan², Jian Chang², Shengli Zhai⁴, Xuncai Chen¹, Yuan Chen¹

Affiliations

¹ The University of Sydney, School of Chemical and Biomolecular Engineering, Sydney, New South Wales 2006, Australia. yuan.chen@sydney.edu.au.
² Nanyang Technological University, School of Chemical and Biomedical Engineering, 637459, Singapore.
³ Koç University, Chemistry Department and KUYTAM Surface Science and Technology Center, Rumelifeneri Yolu, Sarıyer, 34450, Istanbul, Turkey.
⁴ The University of Sydney, School of Chemical and Biomolecular Engineering, Sydney, New South Wales 2006, Australia. yuan.chen@sydney.edu.au and Nanyang Technological University, School of Chemical and Biomedical Engineering, 637459, Singapore.

PMID: 28191583
DOI: 10.1039/c6nr09864a

Abstract

Electrochemical splitting of water to produce oxygen (O₂) and hydrogen (H₂) through a cathodic hydrogen evolution reaction (HER) and an anodic oxygen evolution reaction (OER) is a promising green approach for sustainable energy supply. Here we demonstrated a porous nickel-copper phosphide (NiCuP) nano-foam as a bifunctional electrocatalyst for highly efficient total water splitting. Prepared from a bubble-templated electrodeposition method and subsequent low-temperature phosphidization, NiCuP has a hierarchical pore structure with a large electrochemical active surface area. To reach a high current density of 50 mA cm^-2, it requires merely 146 and 300 mV with small Tafel slopes of 47 and 49 mV dec^-1 for HER and OER, respectively. The total water splitting test using NiCuP as both the anode and cathode showed nearly 100% Faradic efficiency and surpassed the performances of electrode pairs using commercial Pt/C and IrO₂ catalysts under our test conditions. The high activity of NiCuP can be attributed to (1) the conductive NiCu substrates, (2) a large electrochemically active surface area together with a combination of pores of different sizes, and (3) the formation of active Ni/Cu oxides/hydroxides while keeping a portion of more conductive Ni/Cu phosphides in the nano-foam. We expect the current catalyst to enable the manufacturing of affordable water splitting systems.