CuCo‐Layered Double Hydroxide Nanosheets Grown on Hierarchical Carbonized Wood as Bifunctional Electrode for Supercapacitor and Hydrogen Evolution Reaction

Carbonized wood has great potential as a self-supported electrode for energy storage/conversion applications. However, developing efficient and economical bifunctional electrodes by customizing the surface structure remains a challenge. This study proposes a novel multifunctional electrode design strategy, using N/P co-doped carbonized wood (NPCW) as carriers and in situ grows copper nanoparticles (Cu NPs) as nucleation centers to induce vertical growth of CuCo-layered double hydroxid (LDH) nanosheets along the substrate. This method avoids the disordered stacking of catalysts and forms the "carbon-metal-LDH" tertiary conductive network. Therefore, the hierarchical CuCo-LDH@Cu/NPCW is successfully fabricated. Benefiting from the hierarchical ultrathin nanosheet arrays and the strong electronic interactions between CuCo-LDH and Cu/NPCW substrates, CuCo-LDH@Cu/NPCW exhibits a high specific capacitance of 26.24 F cm^-2 at 2 mA cm^-2, with a capacitance retention of 96.70% after 10 000 cycling tests. The assembled symmetric supercapacitor (SSC) achieves a high energy density of 0.80 mWh cm^-2 at 7.50 mW cm^-2. In addition, CuCo-LDH@Cu/NPCW exhibits excellent HER performance with high activity (η₁₀ = 32 mV), low Tafel slope (78 mV dec^-1), and excellent long-term stability. This work realizes the controllable preparation of high-performance bifunctional electrodes and provides new ideas for the application of biomass-derived materials in energy storage and conversion.