Controllable designing of superlattice units of tiled structure and standing structure as efficient oxygen evolution electrocatalyst: self-assembled graphene and hydroxide nanosheet

Layered double hydroxides (LDHs), as an effective oxygen evolution reaction (OER) electrocatalyst, face many challenges in the practical application. One is that bulk materials limit the exposure of active sites, and the other is that controllable assembly of specific structures is difficult to achieve. In this work, based on the exfoliation–assembly strategy, we, for the first time, report novel tiled/standing structures of NiAl-LDH/RGO nanohybrids as highly efficient catalyst for water oxidation in 1.0 M KOH solution. Interestingly, based on our mass protocol, we were surprised to find that there are dynamic evolution structures between NiAl-LDH nanosheets and GO nanosheets (GO-NS). Unambiguous evidences prove the LDH-NS tiling/standing on GO-NS that forms a periodic (LDH/GO)_n superlattice, which was proposed for the first time. NiAl-LDH/RGO-5 (NG-5) nanohybrids possess the lattice unit where LDH-NS are well-organized standing on GO-NS, exhibits excellent electrocatalytic performances with low overpotential of 180 mV and 220 mV at current density of 50 mA cm⁻² and 100 mA cm⁻², and low onset potential of 1.345 V (vs. RHE). In addition, at potential of 1.7 V (vs. RHE), NG-5 composite can drive large current densities of 595 mA cm⁻²; it is better than those of pure NiAl-LDH (123 mA cm⁻²). Furthermore, NG-5 composite exhibits an excellent long-term electrochemical stability for 10 h remained 95.28%. The outstanding electrocatalytic properties above suggest that NG-5 composite is a candidate for the substitution of noble-metal-based catalyst for OER.