N-doped CoNiOOH with optimized band-structure for photo-assisted electrocatalytic overall seawater splitting

Abstract

In this work, an efficient and stable photo-assisted electrocatalyst of N-doped CoNiOOH for overall seawater splitting are proposed. The doped N atoms triggered local contractions of lattice, thereby, promoted the morphologies of products to evolve from nanoflowers to nanowires (NWs), and the obvious electrocatalytic enhancements. Especially under the illumination of AM 1.5 G, the U30-NWs exhibited a photo-assisted cathodic current density from −2.0 to −4.0 mA cm−2 at −0.05 V vs RHE, and also an anodic stability for more than 48 hours in seawater. Our studies reveal that the doped N atom could accumulate more electrons than O atom, leading to the degradation of Co and Ni 3d and O 2p states on either side of Fermi level, thus a p-type feature with the widened band gap and improved UV–visible light absorption. Meanwhile, the corrosion resistance was thus improved due to the chemical stable N-Co(Ni)-N bonds. This work provides a practical strategy towards the H2 production via photo-assisted electrocatalytic seawater splitting.