Surface roughening of nanoparticle-stacked porous NiCoO2@C microflakes arrays grown on Ni foam for enhanced hydrogen evolution activity

Highlights: • Nanoparticle-stacked microflakes arrays structural of NiCoO₂@C-1.0-NF is prepared. • It can increase the exposed active sites. • The activity of NiCoO₂@C-1.0-NF is better than that of NiCo₂O₄ -NF. • Low overpotential, small Tafel slope, and superior durability are achieved. It is a huge challenge to design and develope a highly active and stable non-noble metal electrocatalyst for hydrogen evolution reaction (HER) in alkaline solution. Increasing the active sites and improving conductivity of catalysts are the effective ways to enhance the catalytic performance. Here, nanoparticle-stacked porous NiCoO₂@C microflakes arrays grown on Ni foam (NiCoO₂@C-NF) was synthesized through a simple high temperature heat treatment reaction of the corresponding NiCo₂O₄-NF. The nanoparticle-stacked porous microflakes arrays provide a large amount of exposed active sites. Thus, NiCoO₂@C-NF with 0.072 g of glucose used for their preparation exhibits remarkable performance with −10 and −100 mA cm⁻² for HER at overpotentials of −128 and −184 mV in 1.0 M NaOH solution, respectively. It is much better than that of NiCo₂O₄-NF (a η₁₀ of −221 mV and η₁₀₀ of −379 mV).