NiMn-Layered Double Hydroxide Porous Nanoarchitectures as a Bifunctional Material for Accelerated p-Nitrophenol Reduction and Freestanding Supercapacitor Electrodes

The prolonged reactions for phase and morphology stabilization remain an issue in layered double hydroxides (LDHs), for example, NiMn LDH. The present work proposes a rational strategy for tuning the interfacial surface chemistry in the NiMn LDH phase to obtain grassy-mat-like porous nanoarchitectures. The approach gifts a morphology possessing a high specific surface area available for the ions’ adsorption and desorption, thereby enhancing the extent of reversible reactions. The porous nanoarchitecture displays excellent catalytic activity by reducing p-nitrophenol in just ∼300 s with a rate constant of 0.231 min–1 at a 2 mg mL–1 concentration. Alongside, as a freestanding binder-free supercapacitor electrode, the material delivers a high specific capacitance of ∼568 F g–1 at 1 mA cm–2, which is highest among all NiMn LDH variants prepared at different reaction times. The fabricated symmetric supercapacitor exhibits an excellent energy and a power density of ∼22 W h kg–1 at 1 mA cm–2 and ∼6429 W kg–1 at 10 mA cm–2, respectively. The device retains ∼83% capacitance, at 10 mA cm–2, after 5000 charge–discharge cycles. To the best of our knowledge, this is the first report where NiMn LDH is optimized in a shorter duration and proposed as a competitive bifunctional material for heterogeneous catalysis and supercapacitors.