Iron-nickel layered dihydroxide nanosheet-wrapped single-layer ordered mesoporous carbon with novel riveting structure as a superior composite electrocatalyst for oxygen evolution reaction

Abstract

Iron-nickel layered hydroxide (FeNi LDH) electrocatalysts have low overpotential for the oxygen evolution reaction (OER) in alkaline environments but poor conductivity. The cutting-edge solution is to combine nano-FeNi LDHs with conductive carbon materials. However, the inevitable carbon corrosion during alkaline electrolysis makes it challenging to preserve conductivity between the carbon matrix and nano-FeNi LDHs. This study proposes a novel riveting structural mechanism and a template-replacement synthesis strategy for preparing a high conductivity and stable composite electrocatalyst, i.e., FeNi LDH nanosheet-wrapped single-layer ordered mesoporous carbon (FeNi LDHs@SOMC). The SOMC is produced by carbonizing the resin on the refractory template of MgO/Mg(OH)2 nanosheets, and then the product is immersed in a solution containing Ni2+ and Fe2+ ions for ion exchange under the template induction. Highly active NiFe LDH nanosheets, which are more insoluble than Mg(OH)2, grow from the mesopores of SOMC and wrap the SOMC so that the two are mechanically riveted together. This structure also allows electron transfer from all catalytic sites to SOMC at the nanoscale. The experimental results demonstrated that FeNi LDHs@SOMC is a superior composite electrocatalyst with an OER overpotential of 270 mV at 10 mA.cm−2 and a Tafel slope of 60 mV dec−1. FeNi LDHs@SOMC exhibits extraordinary corrosion resistance and does not degrade after 12 h electrolysis. The study offers an alternative strategy for designing and synthesizing highly hybridized composite electrocatalysts.