Research Projects

Hydrogen is a colourless, odourless gas which is a clean alternative to fuel, fertilizers, and has potential for net zero greenhouse gas emission. Hydrogen is commercially produced by steam reforming of natural gas which is heated to high temperature and pressure in the presence of nickel as catalyst and the process emits ~7 tons of greenhouse gases per ton of hydrogen produced, into the atmosphere. The process is energy intensive as well. Traditionally electrolysis of water has been used for producing hydrogen by splitting water and the H2 produced needs to be kept apart from oxygen immediately as they would recombine spontaneously in addition to being extremely explosive. Hence, the anode and cathode in an electrolyzer, are stacked on either side of an ion selective membrane forming a sandwiched structure which allows the permeation of specific ions (H+ or OH-) and restricts the gases to cross-over. However such methods are energy intensive due to substantial amount of energy required hence non-green, expensive, bulky and prone to membrane degradation. Modern research is increasingly focused on alternative water splitting methods using Advanced Oxidation Processes (AOPs) such as photocatalysis, photoelectrochemical and biological processes. Photocatalysis based water splitting is a green method where light-activated semiconductors photocatalyst electrodes help produce radicals that drive the reaction forward. Traditional photocatalytic water splitting methods are similar to electrolyzers utilizing ion-selective menbranes which leads to membrane degradation at extreme pH of the electrolyte allowing the cross-over of counter ions and gas products, inhibiting hydrogen production rate. To overcome this and enable stable operations at high current densities, noble metals (Pt, Pd, Ir, and Rh) are used as catalysts for cation exchange membrane whereas several different transition metals for anion exchange membranes. However, poor conductivity, large diffusion paths are some of the limitations of such methods. Currently, transition metal chalcogenides (TMCs) have garnered significant attention due to their diverse surface morphological nano/microstructures, excellent conductivity, unique valence electron configuration and inherent photocatalytic water splitting activity. In photocatalysis, a photocatalyst must effectively absorb solar energy to produce an abundance of charge carriers (electron-hole pairs), immediately separate these charge carriers to reduce recombination, strongly adsorb reactants to enable reaction with migrating carriers, and have valence and conduction band energies suitable for the oxidation and reduction reactions. Conventional photochemical reactors where catalyst is suspended into reactants pose several limitations including poor mass and heat transfer, poor light distribution, low surface area for photocatalysis and further downstream processing to separate photocatalyst from the products. In this work, we propose a membraneless microfluidic technology to fabricate a microphotoreactor (MPR) using TMC as a photocatalyst which typically overcomes most of the disadvantages highlighted previously. Microfluidic technology offers immense benefits for electrochemical energy conversion on a microscale and can increase the efficiency and cost feasibility of energy conversion devices. An enhancement in the intrinsic properties is because of its characteristic length ~ microscale which offers improved mass transfer due to low residence time and short radial diffusion. Since the flow in a microfluidic device is laminar, greater control over the flow can be achieved, which will directly facilitate the functioning of a membraneless MPR. We propose developing a standard protocol for fabrication of MPR on a single chip which can be further modified for high-throughput water splitting that can be used for industrial production of hydrogen.