Electrochemical strategies for mitigating CO, and HCI for energy storage and conversion applications

Abstract

The increased encrgy demands of rigorously growing world’s population has augmented the dependence over fossil fucls, causing a challenging conflict for the development of a sustainable socicty. Almost a quarter (24 %) of total CO; emissions come from the industrial sector while energy sector is responsible for around 73.2 % of greenhouse gas emissions. The Conference of the Partics on Climate Change (COP 27) report states that the CO> emissions are projected to rise by 6% i.e. 40.6 Gt in India which is indicative of an alarming situation. Moreover, the current alarming situation would also require electricity’s share in energy sector to increase three folds by 2070. Therefore, electrochemical energy conversion and storage devices are crucial for maximizing the utilization efficiency of generated electricity derived from renewable energy sources. In order to reach “net-zero emissions” by 2050, it would require efforts to decrease the CO; emissions by 5% every year. Perhaps, to combat the consequences of global warming, decarbonisation is the most important yet challenging step. ons Eliminating CO: emissions from the atmosphere is a never-ending process; therefore converting (or reducing) COz is a faster and more efficient way to reduce the adverse effects of CO: onto the environment. Considering both the energy and environmental aspects, Metal- €0, batteries prove to be beneficial, enclosing “wo peas in one pod” which are able to convert CO; to a valuable product and simultaneously generate power. Moreover, hydrochloric acid (HCI) is another waste produced by the production of chloro-organics and 9.3 million tonnes of HCl are produced as byproducts each year, but only 15% is recycled back into Clz, leaving an untapped market for Cl2 recovery that is worth 2.4 billion USD yearly. This excess HCI production can be utilized effectively for Cl production via an electrochemical oxidation pathway. The first chapter of this thesis describe the clectrochemical storage and simultancous conversion of Zn-CO; battery towards the formation of valuc added products. The Zcx! part of thig lh focuses on the cnhancement in the CO; reduction assisted by H2S oxidation which jg “Sfl waste pollutant. Ahead, the chapter 5 focuses on the production of urca by efl'ecu‘,c reduction of N> and CO; clectrochemically. And the last objective of this t‘hesm isto ““‘lb: h industrial waste HCl and transforming it into high valuc feedstock, chlorine (Cly) threy, thi incorporation into novel Zn-ORR/CER batterics. Looking towards the cconomical and efficicnt carbon dioxide (CO2) utilization, metal.Cq, batterics uphold a great potential to enhance the efficiency of CO: conversion to fuels Pertaining to this, in the third chapter, we have fabricated B, N-containing carbon with tubulay morphology (C-BN@600) derived from ionic liquid (IL) and metal-organic framework (MOF) composite as cathode catalyst with Zn foil anode for aqueous rechargeable Zn-CO, bancry The C-BN@600 catalyst demonstrate a remarkable activity towards electrochemica] Co, reduction to methanol with a Faradaic efficiency of 74 % and a Yield rate of 2665 pg h! 'car. The assembled battery consumes CO, continuously and electrochemically convert it methanol during discharge and simultaneously produces electrical energy with a remarkable energy density of 330 Wh kg and a power density of 5.42 mW cm® which is stable for more than 12 days (>300 h, 800 cycles) at 1 mA em?, providing a platform to serve a dual purpose of CO; reduction and energy storage. Further, in another part of this chapter, a significant challenge of competing hydrogen evolution reaction (HER) faced by clectrochemical C0; reduction, was targetted. Herein, Cu;0-PMF as an electrocatalyst showcased a significant enhancement in methanol (CH»OH) faradaic efficiency owing to the suppressed the competing hydrogen evolution reaction (HER) introduced by PMF, leading to an impressive 38% increase in F.E. Morcover, a high-performance Zn-CO, battery was demonstrated to drive water electrolysis for a continuous 22 h and unveiling an astonishing stability of 2600 cycles (4001), for the first time. These findings underline 1 potential of Cu0-PMF & a robust catalyst for CO: its electroreduction and . e application in sustainad energy storage system.