Biomass derived metal free hierarchical porous activated carbon for efficient oxygen evolution reaction

Abstract

The development of high electro-efficient and sustainable metal-free catalysts to replace noble materials is essential for the development of prospective renewable energy conversion and storage systems. Due to its ability to provide clean energy, the oxygen evolution reaction (OER) recently received a lot of interest. Here, we provide an effective "waste to clean energy" concept-based porous-activated carbon from waste rice husk with hierarchical pore architecture for OER. The physicochemical properties of the synthesized activated carbon material were examined by XRD, FESEM, and BET analysis. Characterization of the synthesized activated carbon derived from the rice husk shows a high BET surface area (755 m2/g) with high pore volume. Electro-catalytic performance of the prepared porous-activated carbon has been studied, viz. linear sweep voltammetry, Tafel slope, electrochemical impedance spectroscopy, and cyclic voltammetry in 1 M KOH solution. As an electrocatalytic performance in alkaline media, it shows low-onset potential (1.56 V vs. reversible hydrogen electrode), with a small Tafel slope (61 mV/dec), an overpotential (η10) of 0.47 V, low Rct (212 Ω), and good stability toward OER performance even after 500 cycles. Here, we have also reported the effect of electrochemically active surface area and mass activity effect on the OER performance.