Theoretical investigation of single atom electrocatalysts of polyoxotantalate-supported transition-metals for efficient water-splitting and oxygen reduction reaction Faheem Abbas a , Shamraiz Hussain Talib b , Zonish Zeb a,f , Zheyu Wei a , Sumaira Nazar Hussain c , Yichao Huang a,d,* , Sharmarke Mohamed b , Ahsanulhaq Qurashi b , Yongge Wei a,e,** a Department of Chemistry, Tsinghua University, Beijing 100084, PR China b Center for Catalysis and Separations, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates c Institute of Advanced Study, Shenzhen University, Guangdong 518060, PR China d Department of Materials Science and Engineering, China University of Petroleum, Qingdao 266580, PR China e State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, PR China f School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, PR China A R T I C L E INFO Keywords: Polyoxotantalate (POT) Single-atom catalysis (SACs) Water splitting Oxygen Reduction Reaction Density Functional Theory (DFT) ABSTRACT The rational design of electrocatalysts possess tremendous potential to overcome the energy crisis; however, construction of multifunctional catalysts remains a great challenge. Here, we report the atomic-level under- standing of hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) on a transition metal (TM) atom-anchored polyoxotantalate cluster (POT). Using the spin-polarized density functional theory (DFT) employing VASP, a series of transition metal single-atom catalysts (SACs) are investigated towards finding the multifunctional catalyst. The first principle AIMD simulations were also per- formed to consider stable configuration. Mn/POT ( 0.06 eV) and Pt/POT (0.03 eV) electrocatalysts exhibit excellent HER activity. While the catalyst Pt/POT (0.33 V), and Co/POT (0.43 V) are proven to have potentially remarkable OER activity. In contrast to the noble metal Pt/POT, which achieves an ORR overpotential of (0.34 V), a non-noble metal Co/POT (0.35 V) exhibits a comparable ORR overpotential, making it an economically viable and potential electrocatalyst for ORR. In this study, Pt/POT works as a tri-functional electrocatalyst for HER, OER, and ORR. Co/POT exhibiting bi-functional electrocatalyst for OER and ORR. By analyzing the chemical environment using the solvation model, we find that catalysts with coordination ions (Co/POT, Rh/ POT, and Pt/POT) have excellent OER and ORR activity. Ir/POT has the most minimal activation barrier (0.23 eV) among all the most effective catalysts for HER that have been investigated through IS, TS, and FS config- urations. These findings demonstrate the effective stabilization of single atoms at fourfold-hollow stable active sites for HER, OER, and ORR performance. This study not only enhances the application of POT clusters also serves as a route for future experimentalists to design multifunctional electrocatalysts. 1. Introduction Renewable and environmentally friendly energy sources are essen- tial for mitigating the environmental impact and meeting the urgent demand for cleaner and more sustainable energy solutions [1]. Water splitting plays a crucial part in the generation of green hydrogen energy [2]. This process entails the spitting of water molecules releasing hydrogen and oxygen gases through HER and OER. The ORR is essential for a range of energy conversion and storage mechanisms, notably in fuel cell and metal-air battery systems [3]. Currently, the particularly effective treatment of catalysts for the HER and ORR are based on noble platinum metals [4], while the OER is based on precious metal oxides such as IrO 2 and RuO 2 [5]. However, their high cost and limited avail- ability hinder their practical use in large-scale industrial applications. Electrocatalysts that are earth-abundant, cost-effective, and high- performing are essential for replacing noble metal materials [6]. * Corresponding author at: Department of Chemistry, Tsinghua University, Beijing 100084, PR China. ** Corresponding author at: Department of Chemistry, Tsinghua University, Beijing 100084, PR China. E-mail addresses: yichaoh@upc.edu.cn (Y. Huang), yonggewei@tsinghua.edu.cn, ygwei@pku.edu.cn (Y. Wei). Contents lists available at ScienceDirect Computational and Theoretical Chemistry journal homepage: www.elsevier.com/locate/comptc https://doi.org/10.1016/j.comptc.2024.115044 Received 1 October 2024; Received in revised form 10 December 2024; Accepted 12 December 2024 Computational and Theoretical Chemistry 1244 (2025) 115044 Available online 17 December 2024 2210-271X/© 2024 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.