A Novel Strategy for High Performance Cost-Competitive Solar Water Splitting Enabled with Integrated Bifacial GaAs Photoelectrodes

太阳能从水中生产氢气提供了潜在的可能性，使太阳能能够以化学燃料的形式储存，这种电能是暂时可用的。这种能力将允许能量被暂时储存，然后在需求较高但阳光相对较低的时候进行部署。高效、经济的太阳能从水中生产氢气仍然是一个科学和技术挑战，存在效率、成本和材料耐用性等问题。该项目将研究半导体电子领域的基本概念，以实现新的方法来制造高效、低成本的光电电极，利用阳光中的能量将水分子分解为氢和氧。在所考虑的材料体系中，III-V化合物半导体因其与太阳光良好的相互作用和高效的光载流子产生而具有优异的材料性能，是最有前途的高效太阳能驱动水分离材料之一。这一基础研究项目旨在开发一种高性能、低成本的III-V光电电极材料平台，以应对技术挑战。这项研究的多学科主题将与PI的全面教学和外展努力相结合，包括对本科生和研究生研究人员的培训，特别强调扩大STEM中代表性不足群体的学生的参与，以及针对教育困难的高中生的暑期教育计划。该项目在科学和工程方面取得的进展将有助于继续努力使太阳能氢能发电技术具有成本效益，从而满足社会未来的能源需求。本研究项目的目标是探索III-V化合物半导体光电极的新策略，以解决成本和耐用性方面的根本挑战。电极设计和制造策略将放宽半导体/电解液界面的严格材料要求，提供独特的途径来提高其稳定性，同时允许大幅降低材料成本。为了实现这一目标，该项目将(1)研究基于超薄GaAs基外延材料印刷组装的新型材料平台III-V光电极，(2)从基础水平研究集成双面GaAs光电极在半导体/电解液界面太阳能驱动的水分解中的光电化学行为，(3)建立设计准则和对电荷分离与传输、电子能带配置以及光子增强光吸收的基本理解，(4)探索使用光学厚金属和金属氧化物的新型钝化机制，以及(5)通过互连的GaAs光电极的战略性组装研究无辅助太阳能水分离串联系统的集成路径。该项目的成果将为基本了解超薄GaAs纳米膜光电极的光电化学水分解过程提供坚实的基础，并阐明通过专门的外延设计、纳米级光子管理和双面电极配置的协同作用来增强性能和稳定性的机制。用于确定性材料组装的转印技术将在高效太阳能水分离系统的设计中扩大材料选择，但也为提高成本效益、系统性能和稳定性提供了多样化的集成途径。

Solar-powered production of hydrogen from water offers the potential to enable solar power, which is available on a transient basis, to be stored in the form of a chemical fuel. This capability would allow the energy to be stored temporarily, then deployed during times of high demand but relatively low availability of sunlight. Efficient and cost-effective solar-powered production of hydrogen from water remains a scientific and technological challenge with issues of efficiency, cost, and materials durability. This project will investigate fundamental concepts from the field of semiconductor electronics to enable new approaches to make efficient, low-cost photoelectrodes for splitting water molecules into hydrogen and oxygen using the energy in sunlight. Among materials systems considered, III-V compound semiconductors represent one of the most promising materials for high efficiency solar-driven water splitting due to excellent materials properties pertaining to their favorable interaction with sunlight and efficient photocarrier generation. This fundamental research project aims to develop a high performance, cost-competitive materials platform for III-V photoelectrodes that can address the technology challenges. The multidisciplinary themes of the research will be integrated with the PI's comprehensive teaching and outreach efforts including training for undergraduate and graduate student researchers with a special emphasis on broadening participation of students from underrepresented groups in STEM, as well as summer educational program for educationally-disadvantaged high school students. The scientific and engineering advances achieved in this project will contribute to the continuing efforts to make the technology of solar hydrogen generation cost-effective and therefore address the future energy demand of society. The goal of this research project is to explore novel strategies for III-V compound semiconductor photoelectrodes that can address fundamental challenges in cost and durability. The electrode design and fabrication strategies would relax the stringent materials requirements at the semiconductor/electrolyte interface in ways that provide unique pathways to improve their stability, while allowing substantial reduction in materials cost. To achieve this goal, the project will (1) research a novel materials platform of III-V photoelectrodes based on printed assemblies of ultrathin GaAs-based epitaxial materials, (2) study at a fundamental level the photoelectrochemical behaviors of integrated bifacial GaAs photoelectrodes in solar-driven water splitting at the semiconductor/electrolyte interface, (3) establish design criteria and fundamental understanding of charge separation and transport, electronic band configuration, and photonic enhanced light absorption, (4) explore novel passivation mechanisms using optically thick metals and metal oxides, and (5) investigate integration pathways to tandem systems for unassisted solar water splitting through strategic assemblies of interconnected GaAs photoelectrodes. The outcomes of the project will provide a firm foundation for fundamental understanding of photoelectrochemical water splitting processes with ultrathin GaAs nanomembrane photoelectrodes, and elucidate mechanisms of performance- and stability enhancements by synergistic contributions from specialized epitaxial design, nanoscale photon management, and bifacial electrode configuration. Techniques of transfer printing for deterministic materials assembly will expand materials options in the design of efficient solar water splitting systems but also provide diverse integration pathways for enhanced cost-effectiveness, system performance, and stability.