Microfibril Based Electrocatalytic Electrodes for High Performance Energy Conversion Devices

Abstract

Cellulose in various forms possesses high strength, low density, and a three-dimensional open network structure, making it an ideal candidate for current collectors in energy conversion applications. In this study, a surface rough-cellulose-based bamboo fiber with a unique and naturally convoluted morphology is used to create catalytically active cobalt substrates for energy conversion (HER, OER and MOR) and energy storage applications (Zinc air battery). Our proposed hexafilamentaous bamboo fibre electrode when depostied with catalytically active materials (CoMo, CoFe) delivered promising electrochemical performance. Towards HER the system CoMo/BF delivered 46 mV@ -10 mA cm-2 whereas with CoFe/BF the electrode demonstrated 250 mV@ 50 mA cm-2. Moreover the similar electrode architecture, with a variety of active sites (undercoordinated atoms, lattice mismatches, improved diffusion, number of vacancies and defects) performed excellently as a multifunctional electrode for methanol electrooxidation (MOR) and zinc–air battery (ZAB). Typically, a current density of 20 mA cm-2 at a potential as low as 0.47 vs. Hg/HgO (1.394 V vs. RHE) was evidenced for MOR and an excellent stability under potentiostatic electrolysis was witnessed. Consecutively, in ZAB, the same had delivered a consistent charge–discharge profile at 5 mA cm-2 with a notably lower potential gap (ΔV) of 0.31 V, ensuring a long–term performance with great stability at 1C rate. Besides this, a novel trimetallic catalyst CoMoRu grown on carbon cloth aswell as Bamboo fibre (BF) has been investigated towards HER catalysis. In the CoMoRu catalyst system, the Co component promotes water dissociation while the Ru tweaked in a relatively smaller amount efficiently discharges the protons and evolves the H2 molecule. In addition to this, the Mo component has brought the appropriate electronic configuration in to assist the optimal bonding of Had to the catalytic sites and prevent Ru from getting poisoned by the hydride intermediates. Altogether, our CoMoRu/CC and CoMoRu/BF is able to deliver excellent activity and outperforms the commercial Pt/C with 20 times more the quantity of Ru we have in our CoMoRu/CC and CoMoRu/BF. In particular, CoMoRu/BF and CoMoRu/CC demands just 264 mV and 278 mV to deliver a current density of -150 mA cm-2 while the other controls demand more than 380 mV. This work, thus, promises a new strategy in designing electrode systems that are highly efficient as well as economic as the substrate was obtained from a ubiquitous earth friendly material for energy conversion and storage application.