Research progress of asymmetrically coordinated single-atom catalysts for electrocatalytic reactions

Abstract

Energy has increasingly become the material basis for the development of human society and occupies a strategic position in the national economy. Single-atom catalysts (SACs) are widely recognized as promising...

Understanding the Density-Dependent Activity of Cu Single-Atom Catalyst in the Benzene Hydroxylation Reaction

“…In the second pyrolysis procedure, melamine and cyanuric acid, phytic acid, and l -alanine were nitrogen, oxygen, and carbon sources, respectively. Without phytic acid, only Cu SACs with typical Cu 1 –N 4 single sites were formed, and the maximum density of Cu atoms was less than 1 atoms/nm 2 . − By adjusting the amounts of added Cu 2+ ions, a series of Cu SACs with various Cu densities can be obtained. The highest loading of Cu single atoms was 21.3 wt %, equivalent to a Cu density of 2.4 atoms/nm 2 (Table S1).…”

Asymmetric Coordination Environment Engineering of Atomic Catalysts for CO2 Reduction

“…The resolution of HADDF-STEM images can reach up to 1 Å, allowing a fine distinction between individual atoms [ 90 ]. For instance, Zhang et al reported a conception in which graphene defects capture Ni single atoms as active sites, as shown in Figure 3 a, and identified the presence of di-vacancy defects that trap an atomic Ni species (aNi@Di-vacancy) [ 91 ].…”

Metal–organic framework-derived single atom catalysts for electrocatalytic reduction of carbon dioxide to C1 products

“…SACs have been reported as effective catalysts due to their four-coordinated M-N 4 active sites with a symmetric coordination environment. 131–134 Due to their adjustable geometry and electronic properties, and the high exposure of active sites, M-N 4 moieties are considered one of the main active sites for eCO 2 RR catalytic performance. Therefore, it can be concluded that different activity and selectivity of the products are mainly influenced by the nature of the central metal atoms.…”

“…However, theoretical and experimental results revealed that the high structure/electron symmetry of the M-N 4 moiety, resulting from its symmetrical planar structure, makes it chemically inert to a certain extent, thus reducing the kinetics of the catalytic reaction and hindering it. 39,132,135,136 Therefore, in order to tune the performance of M-N 4 active sites for eCO 2 RR, breaking the symmetrical electronic structure of M-N 4 via a reasonable adjustment of the coordination structure to optimize the electronic structure of the M-N 4 , and subsequently affecting the binding energies for eCO 2 RR intermediates have caught researchers’ attention and have been developed in full swing. By tuning the coordination numbers and introducing second atoms (metal or non-metal), the d orbital of the metal site can be significantly tuned, affecting the catalytic activity for eCO 2 RR.…”