Theoretical Inspection of M₁/PMA Single-Atom Electrocatalyst: Ultra-High Performance for Water Splitting (HER/OER) and Oxygen Reduction Reactions (OER)

Abstract

Developing a cost-effective and highly efficient electrocatalyst with superior catalytic activity is crucial for clean and green water splitting, including the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), and the oxygen reduction reaction (ORR). The single-atom catalyst (SAC) is a breakthrough in industrial catalysis because of the advantages of maximum metal atom utilization, single active sites, strong metal−support interactions, and great potential to accomplish high catalytic performance and selectivity. Herein, we investigate the electrocatalytic performance of a series of SACs supported on a phosphomolybdic acid (PMA) cluster for the HER, OER, and ORR by using first-principles-based calculations. It has been found that the most plausible binding site for the single-metal adatoms is the 4-fold hollow (4H) site over the PMA cluster. Due to the higher stability and catalytic activity of single-metal adatoms, fast electron transfer kinetics is permissible through catalysis. Mainly, Pt 1 /PMA, Ru 1 /PMA, V 1 /PMA, and Ti 1 /PMA realized decent catalytic performance toward the HER due to nearly ideal (ΔG H* = 0) ΔG H* values via the Volmer−Heyrovsky pathway. The Co 1 /PMA (0.45 V) and Pt 1 /PMA (0.49 V) can be active and selective catalysts for the OER with their overpotentials comparable those of to MoC 2 , IrO 2 , and RuO 2 . Among the considered candidates, a non-noble metal Fe 1 /PMA SAC is a promising electrocatalyst for the ORR with an overpotential of 0.42 V, which is lower than that for the most favorable Pt (0.45 V) catalyst. Furthermore, Pt 1 /PMA is an auspicious multifunctional electrocatalyst for overall water splitting (−0.02 V for the HER and 0.49 V for the OER) and a metal-air battery (0.79 V for the ORR) catalyst. The current study is further extended to calculate the kinetic potential energy barrier for the excellent catalytic performance of Co 1 for the OER and Fe 1 for the ORR. The results suggest that the kinetic activation barrier values in all proton-coupled electron transfer steps are in good agreement with the thermodynamic results. It was revealed that the PMA cluster is a promising single-atom support for the HER, OER, and ORR and provides low-cost and highly efficient electrocatalytic activity under normal reaction conditions.

Single-atom catalysts on supported silicomolybdic acid for CO2 electroreduction: a DFT prediction

“…It is found that the TMs prefer to anchor to the 4-H site of Na 4 SiMo 12 , which is consistent with the previous studies. 34,36,52–55 Based on the above analysis, the calculation model of TM@Na 4 SiMo 12 was confirmed and is shown in Fig. 3a, in which the TMs are anchored on the POM 4-H site.…”

A polyoxometalate cluster-based single-atom catalyst for NH3 synthesis via an enzymatic mechanism

“…In this work, the PMA cluster was selected as the support to study single transition metal atom (TM= Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, W, Re, Os, Ir, Pt, and Au) catalysts for the eNRR, since PMA has appeared to be an attractive support to anchor transition metal atoms. 78 It is notable that the Keggin-type PMA cluster is built by 12 MoO 6 octahedra that connect their corners or edges to a central PO 4 tetrahedron, and its fully optimized structure is shown in Fig. S1 †.…”

Theoretical Inspection of TM-P4C Single-Atom Electrocatalyst: Ultra-High Performance for bifunctional Oxygen Reduction and Evolution Reactions

“…According to η OER for FeP4 (0.73 V), NiP4 (0.84 V), CuP4 (2.93 V), PdP4 (0.75 V), AgP4 (1.44 V), PtP4 (0.56 V) and AuP4 (0.67 V), these TMP4 catalysts can also be reported inappropriate for the OER. Remarkably, the CoP4 and RhP4 catalysts exhibit outstanding OER catalytic performance, with the η OER of 0.32 and 0.50 V, respectively, which are better than or comparable to those of Pt1/PMA (0.49 V) [55], RuO2 (0.42 V) [56], ZnN4-edge (0.63 V) [57], and the commonly used IrO2 (0.56 V) [56] catalysts. Thus, the CoP4 and RhP4 can assist as the high active catalysts for the OER.…”

“…(1.75 V), OsP4 (1.72 V) and IrP4 (0.80 V) indicate that the high enough input energies are required for the effective OER catalytic performance. Additionally, previous study [55] has reported that the robust binding interaction and excess energy go against the elimination of related OER intermediates, impeding the active sites and poisoning the catalysts. Hence, the aforementioned TMP4 catalysts are not regarded as the available catalysts for OER.…”