Insights into the role of dual reaction sites for single Ni atom Fenton-like catalyst towards degradation of various organic contaminants

The trade-off of Fenton-like catalysts in activity and stability remains a challenge in practical remediation applications. In this work, we successfully synthesized an efficient and stable catalyst comprised of single nickel (Ni) atoms dispersed on N-doped porous carbon (named Ni-SAs@CN) through a simple micropore confinement strategy. The catalyst exhibited outstanding catalytic performance with 25.8 min-1 turnover frequency for peroxymonosulfate (PMS) activation toward degradation of various organic pollutants (e.g., antibiotics, dyes, and plasticizers) in a wide pH range (4.5-10.8). Electron paramagnetic resonance and in situ Raman analyses demonstrated that both radical (including SO4•- and •OH) and Ni-PMS* dominated nonradical (via electron transfer) pathways played pivotal role in the decomposition of organics. The X-ray adsorption fine structure analysis and computational pieces of evidence demonstrate that the atomically dispersed NiN4 coordination is the intrinsic catalytic site for PMS activation. Meanwhile, pyrrolic N acts as a functional site to anchor target contaminants to the surface region for oxidation. In this process which is benefited from the dual active sites, the target contaminants were degraded via combined radical and nonradical pathways, which significantly boost the overall oxidation and mineralization kinetics.