Theoretical investigation of single atom electrocatalysts of polyoxotantalate-supported transition-metals for efficient water-splitting and oxygen reduction reaction

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 understanding 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 performed 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 configurations. 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.