Research Projects

The search for efficient and sustainable energy conversion has prompted significant research into the development of photoelectrochemical (PEC) water-splitting cells. The direct conversion of solar energy into hydrogen fuel has been the subject of considerable attention worldwide, as it is regarded as a clean and promising energy carrier with the potential to gradually reduce our dependence on fossil fuels. Nevertheless, the solar to hydrogen (STH) efficiency of a PEC system ranges from 3% to approximately 19%.The primary reasons are the narrow visible-light absorption range, rapid photogenerated electron-hole recombination, high surface catalytic overpotential, and most crucially, the sluggish kinetics of the anodic O₂ evolution process. In this regard, we propose a new class of heterostructure photoanodes comprising a combination of a Prussian blue analogue (e.g., AxCoy[Fe(CN)6].nH2O) catalyst material deposited on a range of cobalt and iron oxide-based materials, including Co₃O₄, CoFe₂O₄, and Fe₂O₃. Moreover, the primary objective is to ascertain the underlying charge transfer processes at the proposed heterostructure photoanode interfaces under operational conditions i.e., applied bias. The proposal aims for an operando spectro-electrochemistry approach for the first time in India to study the charge transfer dynamics using time-resolved absorption (TAS) and photoluminescence spectroscopy under applied bias. The following key issues will be addressed towards the development of highly efficient photoanodes: (i) the role of competing loss mechanisms (radiative/non-radiative recombination) limiting the catalytic activity, (ii) the dynamics of intra-material charge transfer (from band states to defect or surface/interface traps/states and vice versa) and, (iii) the impact of inter-material charge carrier transfer dynamics (from metal-oxide to Prussian blue analogue catalyst, from catalyst to reactants) must be considered (iv) finally, the role of different active sites of the photoanodes will be addressed. To this end, an operando transient absorption spectroscopy (TAS) has been developed to elucidate the underlying mechanisms and interfacial processes. Furthermore, time-resolved photoluminescence will be coupled to provide additional information regarding the carrier dynamics, including defect sites' role in the process. Moreover, carrier dynamics will be studied at applied bias in an electrochemical cell to identify the main dynamical properties of charge carriers limiting the catalytic activity in electro- and photo-electrocatalysis. With this, we envision finding the role of dominant intra-material charge carrier dynamics influenced by the active sites and inter-material charge carrier transfer processes driven by band offsets, and potential gradient to the activity in a photo-, electro-catalysis. The detailed summary of the plan is depicted in Figure 1 of the technical document.