Enhancing Water Oxidation Catalysis by Controlling Metal Cation Distribution in Layered Double Hydroxides

The sluggish kinetics of the oxygen evolution reaction (OER), the limiting step of the electrochemical water splitting process, hinders the eventual commercialization of this important renewable energy strategy. Hence, the development of efficient electrocatalysts for this reaction is crucial. Multi-metal-based (hydr)oxides are promising OER electrocatalysts because the electronic interactions between multiple constituent metal cations can potentially enhance electrochemical performances. However, complex compositions may not always lead to positive synergistic effects. The appropriate distribution of the cations is also critical. However, the high dispersibility of cations in these hydroxides renders the control of their distribution challenging. Herein, an approach is reported to control the metal cation distribution in layered double hydroxides (LDHs) to improve their OER performances. Restacking of exfoliated NiFe and CoAl LDH nanosheets leads to electrochemical synergistic effects between different nanosheets. As far as it is known, the restacked LDH described herein exhibits the lowest overpotential (224 mV) and Tafel slope (34.26 mV dec-1) among reported powder-type (hydr)oxide and alloy OER electrocatalysts with more than three different metal cations. Thus, a new design approach is suggested to enhance the electrochemical performances of LDHs. An approach to control the metal cation distribution to enhance the water oxidation performance of layered double hydroxides (LDHs) using their structural property-exfoliation. Restacking leads to electrochemical synergistic effects between different nanosheets. The optimized LDH exhibits the lowest overpotential and Tafel slope among reported powder-type (hydr)oxide and alloy oxygen evolution reaction electrocatalysts with more than three different metal cations.image

Automated summary

This study reports an approach to control the metal cation distribution in layered double hydroxides (LDHs) to improve their water oxidation performance. Restacking of exfoliated nanosheets leads to electrochemical synergistic effects between different nanosheets. The optimized LDH exhibits the lowest overpotential and Tafel slope among reported powder-type (hydr)oxide and alloy oxygen evolution reaction electrocatalysts with more than three different metal cations.