Insights into the effect of substrate adsorption behavior over heme-like Fe1/AC single-atom catalyst

Effect of Electronic Structure over Late Transition-Metal M1–N4 Single-Atom Sites on Hydroxyl Radical-Induced Oxidations

“…The similar H 2 O 2 reaction order values (0.35, 0.37, and 0.41) indicate the same catalytic behavior for activating H 2 O 2 to produce • OH on Co 1 –N 4 , Ni 1 –N 4 , and Cu 1 –N 4 . However, for Fe 1 /ND, the almost zero-order reaction result demonstrates in the RDS over Fe 1 –N 4 is surface oxidation reaction rather than the H 2 O 2 activation process, which further confirms the fast step of H 2 O 2 activation on the Fe 1 –N 4 site. , Combined with LSV and DFT results, it can be reasonably deduced that the d-band center of M 1 –N 4 sites that correlate with the d electron number of the M atom can, to some extent, be an important electronic structure parameter to describe the catalytic behavior of the M 1 –N 4 site to activate the peroxide group. A smaller number of d electrons of the M and higher energy level of the d-band center generally result in stronger interaction between the M 1 –N 4 site and peroxide group as well as the higher electron donation capability from the M 1 –N 4 site to peroxide group, consequently leading to the lower reaction energy for peroxide group activation, which finally leading to the higher catalytic oxidation performance.…”

“…21−28 On the other hand, in most of M 1 /C SACs the well-defined transition-metal single atom center is coordinated with nitrogen molecules to form the M 1 −N 4 site, of which the structure is similar to the active site in natural horseradish peroxidase (HRP). 29,30 This HRPlike M 1 −N 4 active site can denote electron to the peroxide group, thus resulting in • OH generation. Along this way, in the past 5 years, a variety of late transition-metal SACs with HRPlike M 1 −N 4 active sites have exhibited satisfying • OH-induced oxidation properties.…”

“…Recently, the appearance of carbon-supported late transition-metal single-atom catalysts (M 1 /C SACs, M: Fe, Co, Ni, and Cu) provides a new way to realize high catalytic performance in • OH-induced oxidations. − On the one hand, compared to traditional supported metal catalysts, M 1 /C SACs are special types of heterogeneous catalysts with all active transition-metal atoms isolated on the carbon support surface without a metal–metal bond, which gives the maximum active metal utilization superiority in multiple chemical conversion processes. − On the other hand, in most of M 1 /C SACs the well-defined transition-metal single atom center is coordinated with nitrogen molecules to form the M 1 –N 4 site, of which the structure is similar to the active site in natural horseradish peroxidase (HRP). , This HRP-like M 1 –N 4 active site can denote electron to the peroxide group, thus resulting in • OH generation. Along this way, in the past 5 years, a variety of late transition-metal SACs with HRP-like M 1 –N 4 active sites have exhibited satisfying • OH-induced oxidation properties. ,− For example, the Fe 1 –N 4 /graphene catalyst exhibited remarkable performance in direct catalytic oxidation of benzene to phenol at room temperature .…”

“…Moreover, from the projected density of states of each M 1 −N 4 sites (Figure S25 In order to in-depth understand the catalytic mechanism of the peroxide group activation process, the free energy diagram was subsequently performed. Figure 5a, Table S13 29,56 Combined with LSV and DFT results, it can be reasonably deduced that the d-band center of M 1 −N 4 sites that correlate with the d electron number of the M atom can, to some extent, be an important electronic structure parameter to describe the catalytic behavior of the M 1 −N 4 site to activate the peroxide group. A smaller number of d electrons of the M and higher energy level of the d-band center generally result in stronger interaction between the M 1 −N 4 site and peroxide group as well as the higher electron donation capability from the M 1 −N 4 site to peroxide group, consequently leading to the lower reaction energy for peroxide group activation, which finally leading to the higher catalytic oxidation performance.…”

Chemical vapor deposition towards atomically dispersed iron catalysts for efficient oxygen reduction

“…Tremendous efforts have been devoted to anchoring Fe single atoms with suitable coordination structures on the carbon matrix via high-temperature pyrolysis. [13][14][15] However, other forms of iron species, such as Fe nanoparticles and FeC phase are still inevitably generated due to high atom mobility under the elevated temperature, which could lower atom utilization and disturb the four-electron ORR pathway. [16][17][18][19] Therefore, cost-effectively fabricating Fe-N-C single-atom catalysts with outstanding overall ORR performances is still challenging.…”