NiMn layered double hydroxide nanosheets/NiCo2O4 nanowires with surface rich high valence state metal oxide as an efficient electrocatalyst for oxygen evolution reaction

Artikel i vetenskaplig tidskrift, 2018

High valence transition metal oxide is significant for anode catalyst of proton membrane water electrolysis technique. Herein, we demonstrate NiMn layered double hydroxide nanosheets/NiCo 2 O 4 nanowires hierarchical nanocomposite catalyst with surface rich high valence metal oxide as an efficient catalyst for oxygen evolution reaction. A low overpotential of 310 mV is needed to drive a 10 mA cm −2 with a Tafel slope of 99 mV dec −1 , and a remarkable stability during 8 h is demonstrated in a chronoamperometry test. Theoretical calculation displays the change in the rate-determining step on the nanocomposite electrode in comparison to NiCo 2 O 4 nanowires alone. It is found high valence Ni and Mn oxide in the catalyst system can efficiently facilitate the charge transport across the electrode/electrolyte interface. The enhanced electrical conductivity, more accessible active sites and synergistic effects between NiMn layered double hydroxide nanosheets and NiCo 2 O 4 nanowires can account for the excellent oxygen evolution reaction. The catalytic performance is comparable to most of the best non-noble catalysts and IrO 2 noble catalyst, indicating the promising applications in water-splitting technology. It is an important step in the development of hierarchical nanocomposites by surface valence state tuning as an alternative to noble metals for oxygen evolution reaction.