Electric-Field-Assisted Formic Acid Decomposition at Ambient Conditions for Carbon Neutral Hydrogen Production

氢动力燃料电池提供了当今最清洁和最节能的电力来源。 氢（H2）的清洁产生及其分配和储存对传统化石燃料起始材料提出了挑战。 与此相反，本项目在以水（H2O）和二氧化碳（CO2）为原料的再生循环中使用甲酸（HCOOH）作为氢载体。 目前，分解甲酸和产生氢气所需的贵金属催化剂的高成本限制了该技术的商业实施。 该项目研究了一种新的概念，通过这种概念，可以使活性较低，低成本，地球丰富的催化材料，如铜（Cu）或镍（Ni），在电场辅助燃料重整装置的帮助下，像贵金属一样发挥作用，该装置将产生氢气为燃料电池提供动力。 研究人员计划开展几项教育和推广活动，以展示该技术，同时教育各级学生电化学和催化可以促进向可持续能源未来过渡的方式。 基于CO2的可再生燃料电池技术的潜在用途为基于非化石能源的未来能源系统带来了有趣的前景。由于CO2选择性电化学还原为HCOOH的动力学是有利的，因此利用HCOOH分解按需产生H2的再生燃料电池系统对于实际目的是非常有前途的。然而，用于HCOOH分解的最有效的催化剂需要大量昂贵的贵金属，例如铂（Pt）和钯（Pd）。地球上丰富的纯Cu金属在高温下对HCOOH分解表现出高活性和选择性，但在环境温度下没有活性。这种限制可以通过向表面施加最佳强度和方向的电场来规避。所施加的场将显著增加在环境条件下在Cu和Ni金属上HCOOH分解朝向H2/CO2产生的速率，同时防止其导致H2O/CO产生的不期望的副反应。该项目将解决如何施加电场影响HCOOH分解动力学和催化性能的金属表面的基本方面，通过详细的动力学研究，利用场离子/电子显微镜结合原子探针质谱，并通过调查的性质之间的相互作用（方向和相对吸附能）的表面中间体和应用领域使用原位FTIR。 基于这一基本的电场-活性-选择性关系，将制作和评估实验室规模的HCOOH重整系统。 HCOOH分解是研究外加电场对金属催化性能影响的理想模型反应，因为其具有显著的永久偶极矩和高极化率，该奖项反映了NSF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进行评估，被认为值得支持的搜索.

Hydrogen-powered fuel cells offer the cleanest and most energy-efficient source of power available today. Clean generation of hydrogen (H2) and its distribution and storage present challenges with conventional fossil fuel starting materials. In contrast, this project utilizes formic acid (HCOOH) as a hydrogen carrier in a regenerative cycle based on water (H2O) and carbon dioxide (CO2) as the starting materials. Currently, the high cost of precious metal catalysts - needed to decompose the formic acid and generate the hydrogen - limits the commercial implementation of the technology. The project investigates a novel concept by which less active, low-cost, earth-abundant catalytic materials such as copper (Cu) or nickel (Ni) can be made to perform like the precious metals with the aid of an electric field-assisted fuel reforming unit that will generate the hydrogen to power the fuel cell. The investigators plan several educational and outreach activities to demonstrate the technology while also educating students at all levels on the ways in which electrochemistry and catalysis can facilitate the transition to a sustainable energy future. The potential use of CO2-based regenerative fuel cell technology holds interesting prospects for future energy systems based on non-fossil energy sources. Because the kinetics of the selective electrochemical reduction of CO2 to HCOOH are favorable, a regenerative fuel cell system utilizing on-demand H2 production from HCOOH decomposition is highly promising for practical purposes. However, the most efficient catalysts for HCOOH decomposition require a large amount of expensive noble metals such as platinum (Pt) and palladium (Pd). Earth-abundant pure Cu metal has shown both high activity and selectivity toward HCOOH decomposition at elevated temperatures, but no activity at ambient temperatures. This limitation can be circumvented by applying an electric field of optimum strength and orientation to the surface. The applied field will significantly increase the rate of HCOOH decomposition toward H2/CO2 production over Cu and Ni metals at ambient conditions, while preventing its undesired side reaction that leads to H2O/CO production. The project will address fundamental aspects of how this applied electric field influences both the HCOOH decomposition kinetics and catalytic properties of the metal surface through detailed kinetic studies utilizing field ion/electron microscopy in combination with atom-probe mass spectrometry, and by investigating the nature of the interactions (orientation and relative adsorption energy) between surface intermediates and an applied field using in-situ FTIR. Based on this fundamental electric field-activity-selectivity relationship, a lab-scale HCOOH reforming system will be fabricated and evaluated. HCOOH decomposition is an ideal model reaction to investigate the effect of an applied electric field on the catalytic properties of metals because of its significant permanent dipole moment and high polarizability, which makes its chemistry very sensitive to changes in surrounding electric fields.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.