Metal Chalcogenide and Pnictide OER Catalysts: The Impact of the Crystalline Precursor on the Active Amorphous Catalyst

金属硫化物和硫化物OER催化剂：晶态前体对活性非晶态催化剂的影响开发地球上丰富、廉价的材料，可以将水化学转化为氧气和氢气，这是寻求建立可持续能源未来的重要目标。这种催化过程被称为水电解或水分解，用于以环境友好的方式生产氢气。氢气用于许多行业(如石油加工)，也可用作运输和其他用途的燃料。目前，金属硫化物(如镍和硫)和金属硫化物(如钴和磷)材料作为富稀土化合物对水氧化反应(水氧化反应是涉及水分解的两个反应之一)具有良好的催化性能，但其真实的化学组成和结构尚不清楚。在这个项目中，Buddie Mullins博士正在对金属硫化物和金属硫化物材料进行实验，并研究它们在水氧化反应中的化学和结构变化。穆林斯博士通过他的研究积极参与科学公共意识和促进活动，鼓励科学、技术、工程和数学(STEM)学科的学生参与和智力发展。这些活动包括为高中生和大学本科生提供实验室实习，目的是鼓励这些学生(特别是女性和那些在STEM历史上代表性不足的学生)在STEM领域追求职业生涯。在化学系化学催化计划的资助下，Buddie Mullins教授正在努力验证或反驳以下假设：(I)金属硫化物(MC)和金属多金属(MP)电催化剂只是高活性金属氧化物(MO)电催化剂的前体；(Ii)MC或MP的底层不影响催化性能。显然，在水氧化条件下，MCS和MPS的外层转变为MOS。在这种转变过程中，形成了一种无定形的高表面积薄膜，它比它的晶体氧化物类似物更具催化活性。穆林斯教授正在研究这种无定形薄膜的形成机制及其增强的活性。他还通过掠射角物理气相沉积的方法合成了纳米和致密的MC和MPS薄膜，作为模型电催化剂，这种方法可以重复地生成电催化薄膜。穆林斯正在用许多不同的非原位表征技术来探测这些薄膜，包括分子束和热解吸质谱，用于表征和测量表面积。穆林斯博士积极参与向所有年龄段的学生，特别是那些在科学界历史上代表性不足的学生推广科学和科学教育。这是通过视频、实习和公开演示实现的；这些活动支持研究项目的更广泛影响。

Metal Chalcogenide and Pnictide OER Catalysts: The Impact of the Crystalline Precursor on the Active Amorphous CatalystDeveloping earth-abundant, cheap materials that can chemically transform water into oxygen and hydrogen is an important goal in the quest to build a sustainable energy future. This catalytic process, referred to as water electrolysis or water-splitting, is used to produce hydrogen in an environmentally-friendly manner. Hydrogen is employed in many industries (e.g., petroleum processing) and could also be used as a fuel for transportation as well as other purposes. Currently metal-chalcogenide (e.g., nickel and sulfur) and metal-pnictide (e.g., cobalt and phosphorous) materials show great promise as earth-abundant compounds with good catalytic properties for the water oxidation reaction (which is one of the two reactions involved in water splitting) but their true chemical compositions and structures are not well-understood. In this project, Dr. Buddie Mullins is conducting experiments on metal-chalcogenide and metal-pnictide materials and studying their chemical and structural transformations during the water oxidation reaction. Dr. Mullins is actively involved in scientific public awareness and promotion activities through his research that encourage the participation and intellectual development of students in science, technology, engineering and mathematics (STEM) disciplines. These activities include laboratory internships for high school students and college undergraduates with the aim of encouraging these students (especially women and those historically underrepresented in STEM) to pursue careers in the STEM fields.With funding from the Chemical Catalysis Program of the Chemistry Division, Professor Buddie Mullins is working to verify or disprove the hypothesis that (i) metal-chalcogenide (MC) and metal-pnictide (MP) electrocatalysts are simply precursors to highly active metal-oxide (MO) electrocatalysts and (ii) that the underlying layers of MC or MP don't influence the catalytic performance. It is clear that the outer layers of MCs and MPs transform into MOs under water oxidation conditions. During this transformation an amorphous high surface area film is created that is more catalytically active than its' crystalline oxide analog. Professor Mullins is studying the mechanism by which the amorphous film is created as well as its enhanced activity. He is also synthesizing both nanocolumnar and dense films of MCs and MPs for use as model electrocatalysts by glancing angle physical vapor deposition, which can reproducibly create electrocatalyst films. Mullins is probing the films with many different ex situ characterization techniques, including molecular beams and thermal desorption mass spectrometry for characterization and measurement of the surface area. Dr. Mullins is actively involved in promoting science and science education to students of all ages and especially those historically underrepresented in the sciences. This is accomplished via videos, internships and public demonstrations; these activities support the broader impacts of the research project.