NSF-BSF: Controlling Phase Selectivity and Electrocatalytic Activity of Transition-Metal Dichalcogenide Overlayers in Core-Shell Nanoparticles for CO2 Reduction

廉价催化剂材料的发现和优化是满足对清洁和可持续能源的迫切需求的基础。特别是，将二氧化碳（CO2）转化为有价值的化学原料和燃料，再加上可再生能源，为碳排放的可持续管理提供了一条有希望的途径，但由于缺乏合适的催化剂，该过程目前效率低下。为了应对这一挑战，该项目由美国国家科学基金会（NSF）和美国-以色列两国科学基金会（BSF）合作机会NSF 17-520资助，将支持研究一类新的催化剂，使二氧化碳有效转化为更高价值的化学品和燃料。来自马萨诸塞州阿默斯特大学和本古里安大学的一组研究人员将分析和评估催化剂，这些催化剂是由地壳中丰富的材料制成的，大规模加工成本低廉。该项目的更广泛的社会影响包括在马萨诸塞大学阿默斯特分校招募和指导代表性不足的少数民族学生，以及在马萨诸塞州西部和以色列的社区推广。美国和以色列的科学合作将通过合作机构之间的研究生交流得到加强。二氧化碳的电化学还原是关闭碳循环的一种有前途的途径，但目前由于缺乏在低过电位下既有活性又有选择性的催化剂而受到阻碍。该项目的重点是地球丰富的电催化剂，基于钼（Mo）和钨（W）层状过渡金属二硫属化物（TMDC）家族的半金属相，目标是满足这些苛刻的催化性能要求。一个集成的理论合成表征方法有利于过渡金属核-TMDC壳纳米粒子的合理设计，其中Mo和W TMDC的电化学活性的半金属相优先稳定于基态的半导体相。特别地，半金属相的稳定化不依赖于常规的动力学捕获方法，而是通过金属核和TMDC壳之间的电荷转移相互作用来实现，这提供了针对不期望的半金属至半导体相变的更大程度的鲁棒性。这种相工程的核壳纳米粒子的发展取得了根本性进展，在二维材料和纳米催化领域产生了深远的科学影响，同时也使可再生能源技术成为可能。该研究计划与少数民族服务机构的本科生的形成性研究机会相结合，从而培养下一代材料科学家和工程师。向马萨诸塞州西部和以色列的学生和广大公众介绍与纳米技术及其在可再生能源中的应用有关的问题，进一步扩大了这项研究的影响。通过合作机构之间的人员交流，美国和以色列的科学合作将得到加强。该奖项反映了NSF的法定使命，并且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。

The discovery and optimization of inexpensive catalyst materials is fundamental to fulfilling the urgent need for clean and sustainable sources of energy. In particular, conversion of carbon dioxide (CO2) to valuable chemical feedstocks and fuels, when complemented by renewable sources of energy, offers a promising route for sustainable management of carbon emissions, but the process is currently inefficient due to the lack of suitable catalysts. To address this challenge, this project, funded under the National Science Foundation (NSF) and US-Israel Binational Science Foundation (BSF) collaborative opportunity NSF 17-520, will support investigation of a new class of catalysts that enable the efficient conversion of CO2 to higher-value chemicals and fuels. A team of researchers from the University of Massachusetts Amherst and Ben Gurion University will analyze and evaluate catalysts that are engineered from materials that are abundant in the Earth's crust and inexpensive to process at large scales. The broader societal impacts of this project include recruitment and mentoring of underrepresented minority students at UMass Amherst, and outreach to the communities in Western Massachusetts and Israel. US-Israel scientific collaboration will be enhanced by graduate student exchanges between the partner institutions.Electrochemical reduction of CO2 is a promising avenue for closing the carbon cycle but is stymied at present by the lack of catalysts that are both active and selective at low overpotentials. This project focuses on earth-abundant electrocatalysts, based on semi-metallic phases of the molybdenum (Mo) and tungsten (W) family of layered transition-metal dichalcogenides (TMDCs), with the goal of addressing these demanding catalytic performance requirements. An integrated theory-synthesis-characterization approach facilitates rational design of transition-metal core-TMDC shell nanoparticles in which the electrochemically-active, semi-metallic phases of Mo and W TMDCs are preferentially stabilized over the ground-state, semiconducting phases. In particular, stabilization of the semi-metallic phases does not rely on conventional kinetic trapping approaches, being achieved instead by charge-transfer interactions between the metallic cores and the TMDC shells, which provides a greater degree of robustness against the undesirable semimetal-to-semiconductor phase transition. Fundamental advances in the development of such phase-engineered, core-shell nanoparticles project far-reaching scientific impact in the fields of two-dimensional materials and nanoscale catalysis, while also enabling renewable energy technologies. The research program is integrated with formative research opportunities for undergraduates from minority-serving institutions thereby nurturing the next generation of materials scientists and engineers. Presentations to the students and the broader public in Western Massachusetts and Israel on issues associated with nanotechnology and its applications in renewable energy further extend the impact of this research. US-Israel scientific collaboration will be enhanced by personnel exchanges between partner institutions.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.