Highly active atomic Cu catalyst anchored on superlattice CoFe layered double hydroxide for efficient oxygen evolution electrocatalysis

Abstract

Developing active, natural abundant and non-expensive electrocatalysts for large scale production and storage of clean hydrogen (H 2 ) fuel is a prerequisite to drive stable water splitting reaction. Herein, atomic Cu species loaded on hierarchical flower-like CoFe layered double hydroxides (LDHs) superlattice (denoted as Cu x /CoFe LDHs) were firstly fabricated by a facile co-precipitation method followed by a room temperature treatment to load the atomic Cu species from alkaline copper salt solution. The superlattice structure was proved by the high resolution transmission electron microscopy (HRTEM). Remarkably, benefiting from high level long ordering associated with vacant cation sites and defects, the unique superlattice structural features and the atomic Cu % loading onto the LDHs matrix, the obtained Cu x /CoFe LDHs electrocatalyst exhibited superior activity and stability for oxygen evolution reaction (OER). The loaded atomic Cu species improves the electronic structure and provides more exposed active sites due to synergetic electron coupling between Copper and the LDHs. These atomic species have outstanding potentials for achieving high selectivity and reactivity in electrocatalysis and heterocatalysis. Importantly, the efficient resulted Cu 4.76 /CoFe LDHs electrode in which the atomic Cu % loading ratio is 4.76% showed the best electrocatalytic activity which only required the much lower overpotential of 253 mV to reach 10 mA/cm 2 and a small Tafel slope of 63 mV/decade in 1 M KOH. This electrocatalyst possessed unique superior features to many other state-of-the-art earth-abundant electrocatalysts. This work paves a facile and novel method for enhancing the catalytic activity of CoFe LDHs based electrocatalyst, which may be extended to the synthesis of future electrocatalysts having highly active OER performance. • Novel synthesis of Cu x /CoFe LDHs electrocatalysts via co-precipitation followed by atomic Cu species loading. • 3D hierarchical porous flower-like morphologies offering more accessible channels and active sites. • Electrons transfer from M (Co or Fe) to Cu via M–O–Cu bonds. • The Cu 4.76 /CoFe LDHs electrode showed much lower overpotential and small Tafel slope. • The loaded atomic Cu species improves the electronic structure and provides more exposed active sites.