Bio-inspired photonics and surface engineering for sustainable energy materials

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The rapid consumption of fossil fuels and its consequential ecological and environmental issues necessitate the exploration of solutions centered around renewable green resources. Among the various alternative methods of green energy production, photoelectrocatalysis (PEC) emerges as a highly promising approach for simultaneously addressing energy and environmental concerns. PEC offers the potential to store intermittent yet abundant solar energy in the form of high-density fuels, notably hydrogen (H2). One of the major milestones in achieving efficient hydrogen production lies in the optimization of the photo absorbers, involving processes that enhance the absorption of solar radiation and generate a sufficient number of electrons (e-) and holes (h+) to drive the thermodynamically uphill redox processes, as well as material surface morphology and chemical structure that interact with other phases. - the research questions the project is trying to address/the objectives of the project:1. This project aims to develop novel fabrication methods for photocatalytic materials. The research questions we aim to address are as follows: In heterogeneous photocatalytic processes, inexpensive and abundant metal oxides (MOs) with bandgaps in the UV-Vis range are commonly employed as catalysts. 1) To achieve efficient photocatalytic water splitting, research on band gap engineering of MOs needs to be developed to align with the energy requirements of the overall water splitting process. 2) Also, many wide-bandgap MO semiconductors encounter limited catalytic activity for hydrogen production within the visible spectral range, thereby impeding the sufficient utilization of solar radiation. 3) Moreover, good chemical stability and efficient charge separation between photoexcited electrons (e-) and reactive holes (h+) are critical for both photocatalysts and electrochemical reactions.2. In terms of objectives in this project, we focus on harnessing the photonic characteristics of materials, with the objective of enhancing the photocatalytic performance of MOs. This will be accomplished by improving the nanoengineered structure of photocatalytic materials, facilitating changes in MO bandgap, providing high surface area, and enhancing the mobility of (e-) - (h+) pairs.Specifically, 1) Our approach involves the synthesis of sustainable photonic nanostructures, specifically crystalline structures with controlled long-range and short-range crystalline orders, which serve as template materials for MOs. 2) The implementation of MO structures in the form of photonic crystals is anticipated to enhance the photocatalytic performance of MOs within the visible light range. This enhancement can be achieved through significantly augmented light-material interaction at the edge of the photonic bandgap via the stop band, a frequency range that forbids propagation. 3) The crystal structure and overlap of the photonic and electronic band gaps in these structures extend the lifetimes of (e-) - (h+) pairs, thereby facilitating more efficient charge separation. 4) Tuning of the surface texture is undertaken to strike a balance between light-harvesting capacity, crystal structure, and potential losses during bubble formation and release.