CAS: Bimetallic Transition Metal Phosphide Nanostructures as High-Efficiency, Earth-Abundant, and Durable Catalysts for Electrochemical Water Splitting

在化学系化学催化项目的支持下，弗吉尼亚联邦大学的Indika Arachchige教授和Ka Un Lao教授正在研究金属磷化物纳米颗粒的基本特性，作为将水分解成环境友好型氢和氧燃料的有效催化剂。用电（电化学水分解）从水中生产氢的廉价方法将为可再生燃料提供丰富的来源。目前，用于水分解的最活跃的催化剂是由昂贵的稀有金属如铂组成的。该项目将开发新的化学合成方法，从金属磷化物中生产更便宜、更丰富的高效催化剂。通过加入多个金属原子修饰颗粒表面，提高了磷化物催化剂的活性。研究团队将合成和催化专业知识与量子化学计算和人工智能相结合，以全面了解颗粒大小，形状和组成对关键催化性能和化学稳定性的影响。该项目的合作性质为研究生和本科生提供多学科培训和指导，以发展催化剂设计和合成、计算化学和纳米科学方面的技能。在里士满公立学校的夏季推广活动中，K-12学生接触到了尖端的纳米化学和催化项目，并开发了适合他们年龄的纳米科学教育模块，影响了数百名未被充分代表的少数民族学生。电催化使水分解提供了一个令人兴奋的机会，生产环境友好的燃料，为人类活动提供动力。过渡金属磷化物（TMPs）已成为丰富的水电解催化剂，通过添加增效金属来改变其表面亲和力以及氢（HER）和氧（OER）反应的动力学和机制，可以极大地增强其活性。支撑其高效应用的是合理和可预测地实现精确控制催化剂特性的能力，包括直接影响HER/OER活性、稳定性和耐久性的特定催化剂结构、表面切面、形态和组成。该计划的目标是利用综合的理论和实验方法来生产具有控制内在特征的双金属TMP纳米结构，作为HER和OER的高效电催化剂。采用胶体化学方法制备了一系列具有不同尺寸、组成和形态的TMP纳米结构。在密度泛函理论模拟和机器学习模型的指导下，深入探讨了协同金属合金化对电荷分布、离子吸附、氧化/还原动力学和机理以及稳定性的影响。这些理论指导的实验旨在探索具有优异水裂解活性和稳定性的特定催化剂结构、晶体面、表面末端和成分，这与HER和OER的潜在动力学和机制有关。这些努力揭示了同时控制纳米结构、晶体面、形态和组成对水分解活性的基本影响，并制定了路线图，指导研究人员生产高效、健壮的TMP纳米催化剂，用于合理设计电化学反应器。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Chemical Catalysis program in the Division of Chemistry, Professors Indika Arachchige and Ka Un Lao of the Virginia Commonwealth University are studying the fundamental properties of metal phosphide nanoparticles as effective catalysts for splitting water into environmentally friendly hydrogen and oxygen fuel. The inexpensive generation of hydrogen from water using electricity (electrochemical water splitting) would provide an abundant source of renewable fuel. Currently, the most active catalysts used in water splitting are comprised of expensive and rare metals such as platinum. This project will develop new chemical syntheses to produce efficient catalysts from metal phosphides that are less expensive and abundant. The activity of the phosphide catalysts is improved by modifying the surface of the particles by incorporating multiple metal atoms. The research team combines synthesis and catalysis expertise with quantum chemistry calculations and artificial intelligence to garner a thorough understanding of the effects of particle size, shape, and composition on key catalytic properties and chemical stability. The collaborative nature of this project provides multidisciplinary training and mentoring for graduate and undergraduate students, to develop skills in catalyst design and synthesis, computational chemistry, and nanoscience. The summer outreach to Richmond Public Schools exposes K-12 students to cutting-edge nanochemistry and catalysis projects, and develops age-appropriate nanoscience educational modules impacting hundreds of underrepresented minority students.Electrocatalysis enabled water splitting presents an exciting opportunity to produce environmentally benign fuel to power human activities. Transition metal phosphides (TMPs) have emerged as earth abundant catalysts for water electrolysis and their activity can be enormously augmented by admixing synergistic metals to modify the surface affinity and the kinetics and mechanisms of hydrogen (HER) and oxygen evolution (OER) reactions. Underpinning their efficient application is the ability to rationally and predictably achieve precisely controlled catalyst features, including specific catalyst structures, surface facets, morphologies, and compositions, that directly impact the HER/OER activity, stability, and durability. The objective of this program is to exploit a comprehensive theoretical and experimental approach to produce bimetallic TMP nanostructures with control over intrinsic features as high efficiency electrocatalysts for HER and OER. A series of TMP nanostructures having various sizes, compositions, and morphologies are produced by colloidal chemistry methods. The influences of synergistic metal alloying on charge distribution, ion adsorption, oxidation/reduction kinetics and mechanisms, and stability are thoroughly probed with experiments guided by density functional theory simulations and machine learning models. The theory-guided experiments are designed to probe specific catalyst structures, crystal facets, surface terminations, and compositions that show superior water splitting activity and stability, which are correlated to underlying kinetics and mechanisms of HER and OER. These efforts reveal the fundamental influences of simultaneous control over nanostructure, crystal facets, morphology, and composition on water splitting activity and develop roadmaps that guide researchers to produce highly efficient, robust TMP nanocatalysts for the rational design of electrochemical reactors.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.