Surface and interface engineering of CoNi layered double hydroxides for efficient methanol oxidation reaction

In this report, surface atomic engineering (P doping) and interface molecular engineering (coupling with reduced graphene oxide) were adopted to adjusting the chemical compositions, morphological structure, electronic properties and methanol oxidation reaction (MOR) activity of CoNi layered double hydroxides (CoNi LDHs). Low-electronegative P atom doping can improve the conductivity and induce a synergistic effect to increase MOR activity. Coupling P doped CoNi LDHs (P-CoNi LDHs) with reduced graphene oxide (rGO) to produce composite structures (rGO/P-CoNi LDHs) can impart novel electronic and morphological properties, thereby boosting the MOR activity even further. The P-CoNi LDHs with different morphology and the rGO/P-CoNi LDHs composite were prepared by a cyclic voltammetry (CV) deposition method, which can be directly used as a binder free electrode for MOR. Morphology characterization and electrochemical results indicate that the uniform red-bayberry like P-CoNi LDHs, which were prepared in water solvent, exhibit the highest MOR activity compared with those prepared in alcohol-water component electrolyte, which was 2 times higher than the undoped CoNi LDHs. The introduction of rGO enhance the MOR activity and stability even further, the MOR activity of ball flower like rGO/P-CoNi LDHs was 1.7 times higher than P-CoNi LDHs, the current density retention is 97% after 1000 s at 0.6 V, which is higher than that of P-CoNi LDHs (87%), but the long-term stability still remains to rise. This report may provide a new insight into design and prepare high electrochemical performance LDHs.