Hierarchical CoNiO2 Microflowers Assembled by Mesoporous Nanosheets as Efficient Electrocatalysts for Hydrogen Evolution Reaction.

In order to alleviate the energy crisis and propel a low-carbon economy, hydrogen (H2) plays an important role as a renewable cleaning resource. To break the hydrogen evolution reaction (HER) bottleneck, we need high-efficiency electrocatalysts. Based on the synergistic effect between bimetallic oxides, hierarchical mesoporous CoNiO2 nanosheets can be fabricated. Combining physical representations with electrochemical measurements, the resultant CoNiO2 catalysts present the hierarchical microflowers morphology assembled by mesoporous nanosheets. The ultrathin two-dimensional nanosheets and porous surface characteristics provide the vast channels for electrolyte injection, thus endowing CoNiO2 the outstanding HER performance. The excellent performance with a fewer onset potential of 94 mV, a smaller overpotential at 10 mA cm-2, a lower Tafel slope of 109 mV dec-1 and better stability after 1000 cycles makes CoNiO2 better than that of metallic Co and metallic Ni.