Priyadarsini Adyasa, Mallik Bhabani S
Department of Chemistry, Indian Institute of Technology Hyderabad, Sangareddy 502285, Telangana, India.
ACS Omega. 2021 Feb 19;6(8):5368-5378. doi: 10.1021/acsomega.0c05538. eCollection 2021 Mar 2.
Molecular oxygen and hydrogen can be obtained from the water-splitting process through the electrolysis technique. However, harnessing energy is very challenging in this way due to the involvement of the 4e reaction pathway, which is associated with a substantial amount of reaction barrier. After the report of the first N-doped graphene acting as an oxygen reduction reaction catalyst, the scientific community set out on exploring more reliable doping materials, better material engineering techniques, and developing computational models to explain the interfacial reactions. In this study, we modeled the graphene surface with four different nonmetal doping atoms N, B, P, and S individually by replacing a carbon atom from one of the graphitic positions. We report the mechanism of the complete catalytic cycle for each of the doped surfaces by the doping atom. The energy barriers for individual steps were explored using the biased first-principles molecular dynamics simulations to overcome the high reaction barrier. We explain the active sites and provide a comparison between the activation energy obtained by the application of two computational methods. Observing the rate-determining step, that is, oxo-oxo bond formation, S-doped graphene is the most effective. In contrast, N-doped graphene seems to be the least useful for oxygen evolution catalysis compared to the undoped graphene surface. B-doped graphene and P-doped graphene have an equivalent impact on the catalytic cycle.
分子氧和氢可以通过电解技术从水分解过程中获得。然而，由于涉及4e反应途径，这种方式获取能量极具挑战性，该反应途径伴随着大量的反应势垒。在首个氮掺杂石墨烯作为氧还原反应催化剂的报告发表后，科学界开始探索更可靠的掺杂材料、更好的材料工程技术，并开发计算模型来解释界面反应。在本研究中，我们通过从石墨位置之一替换一个碳原子，分别用四种不同的非金属掺杂原子N、B、P和S对石墨烯表面进行建模。我们报告了每个掺杂表面上掺杂原子的完整催化循环机制。使用有偏的第一性原理分子动力学模拟来探索各个步骤的能垒，以克服高反应势垒。我们解释了活性位点，并对应用两种计算方法获得的活化能进行了比较。观察到速率决定步骤，即氧-氧键的形成，硫掺杂的石墨烯最为有效。相比之下，与未掺杂的石墨烯表面相比，氮掺杂的石墨烯似乎对析氧催化最无用。硼掺杂的石墨烯和磷掺杂的石墨烯对催化循环有同等影响。
