Becoming more energy sustainable is a major current societal goal, which, of necessity, involves greater use of sunlight as a primary source of energy. However, if solar energy is ever to displace fossil fuels as our main energy source, it could only do so if we solve the energy storage problem.
The first portion of the talk will introduce our research efforts to develop novel nanomaterials and architectures to convert light energy directly into high free energy materials that can be used as chemicals, thereby storing the solar energy in a high energy density and transportable form. The photoelectrochemical systems were developed utilizing several potential concepts including: (i) semiconductor and/or Schottky junction based nanostructures employing earth abundant elements (e.g. SnS photocathodes; BiVO4/WO3 photoanodes); (ii) electrochemically manufactured multi-junction cells (a collaborative effort with Prof. John Stickney’s group at UG) and (iii) oxide encapsulated stable photoelectrochemical nanoreactors. The structures created were able to generate high-value oxidation (Cl2) and reduction (H2) products sustainably for at least 3 hours in acidic medium.
The second part of the talk will focus on our efforts to develop grid-scale energy storage device that integrates technical advantages of redox flow batteries, and non-Li sold electrode batteries into a single device. Technically, our approach replaces the traditional aqueous solution of redox active molecules found in typical redox flow batteries with circulating hydrophilic carbon particles (“flowable electrodes”) coated with earth-abundant redox-active solids. The above concept was successfully used to demonstrate several non-Li-based battery chemistries including zinc-copper, zinc-manganese oxide, zinc-bromine, and zinc-sulfur, providing a pathway for potential applications in medium and large-scale electrical energy storage