Biowaste-Derived Enhanced Conductive Carbon Composites as an Ultralow-Cost Electrocatalyst for Oxygen Evolution Reaction

Developing cost-effective and highly efficient electrocatalysts for oxygen evolution reaction (OER) is urgently desired for the large-scale application of water electrolysis and rechargeable hydrogen fuel cells. In this regard, we proposed a feasible hydrothermal-assisted strategy to transform lignin waste into an ultralow-cost OER electrocatalyst, which is composed of highly conductive carbon materials with low Co-doping (similar to 3.54 wt % Co). Notably, the hydrothermal pretreatment could optimize the chemical construction of lignin and further affect its carbonization behavior, resulting in the enhanced conductivity and the formation of 2D carbon nanosheets in the hydrothermal-modified lignin-derived carbon (HTLC), which is conducive to electron/mass transfer for OER electrocatalysis. Profiting from the virtues of large active surface area, fast charge transfer kinetics, and high hydrophilicity, the as-prepared catalyst (CoOx-HTLC) exhibits a competitive OER activity at high current densities, along with preferable electrochemical stability in 1.0 M KOH solution, as compared with the state-of-the-art RuO2. Meanwhile, CoOx-HTLC can achieve 10113 mA<middle dot>mg(Co)(-1) at the potential of 1.82 V (vs RHE), 20 times larger than pure CoOx NPs. This work offers a new approach that combines lignin waste with sustainable energy technology, which not only prepares ultralow-cost electrocatalysts but also enables the value-added utilization of lignin waste.