Rational design of microflower-like manganese-doped ultrathin cobalt hydroxide nanosheets as bifunctional electrode materials for electrochemical sensing and supercapacitor applications

Noble metal-based electrocatalyst must be replaced for electrochemical applications by earth-rich, highly active, low-cost, and highly efficient dual-function electrocatalysts. In this study, transition metal-based hydroxides (TMHs), such as 2D manganese-doped cobalt hydroxide (Mn-Co(OH)2) ultrafine nanosheets, are investigated using a very simple large-scale co-precipitation method for efficient electrochemical sensing (nitrofurantoin (NFT)) and supercapacitor (SC) applications. The characterization results show that the porous and large surface area, polycrystalline nature, confinement of the 2D orientation, and strong synergistic effect contribute to the admirable electrochemical concert of Mn-Co(OH)2 for both sensing and SC applications. CV, GCD, EIS, and DPV techniques are used to thoroughly investigate electrochemical and physicochemical properties. As an electrochemical sensor, the Mn-Co(OH)2 modified disposable screen-printed carbon electrode (Mn-Co(OH)2/SPCE) shows excellent electrochemical assets for NFT detection with broad linear ranges (0.05–219 μM and 262–641 μM), low detection limit (0.012 μM) and good anti-interference ability. The obtained specific capacitance of Mn-Co(OH)2 is 348.8 F g−1 at 1 A g−1 with a maintenance capacitance of 80.76 % after 5000 cycles at 10 A g−1. The enhanced electrochemical behavior of Mn-Co(OH)2 may be related to the fast diffusion pathways of Mn doping and the enhanced redox reaction (cobalt ions) of the flower-like ultrathin nanosheets owing to their high surface area (214 m2/g). The characterization results and electrochemical performance (sensing and SCs) provide important and noteworthy insights into the synthesis of noble metal-free and high-efficiency transparent 2D TMHs nanosheets with high performance that can be widely used in various applications.