An Earth‐Abundant Ni‐Based Single‐Atom Catalyst for Selective Photodegradation of Pollutants

Abstract

Highly efficient catalytic technologies are urgently needed to remove pharmaceutical pollutants from water. In this work, the preparation, characterization, and photocatalytic performance of an earth‐abundant Ni‐based heterogeneous catalyst featuring highly dispersed Ni species over nanosheets of carbon nitride are reported. The absence of any metallic nickel phase has been confirmed by spectrometric analyses, unveiling the NiN environment for the metal centers and attaining synergistic interfacial carrier transfer via NNiN coordination. By combining advanced characterizations with kinetic investigations, it is demonstrated that these newly formed isolated single atoms of Ni act as a bridge, facilitating faster electron transfer, increasing the charge density on Ni, and reducing the photocarrier transfer barrier. Compared to literature precedents, this substantially enhances the degradation of gemfibrozil, a model pharmaceutical pollutant found in wastewater, reducing the formation of toxic benzenic byproducts during photooxidation. This effect, which is not observed over conventional nanoparticle‐based materials, discriminates the role of single‐atom and nanoparticle‐based catalysis during degradation of pollutants. This work opens new avenues in designing selective and earth‐abundant photocatalysts for advanced oxidation processes, showing the importance of atom coordination to control the surface and catalytic properties of single‐atom materials.

Mineral Modulated Single Atom Catalyst for Effective Water Treatment

“…The N 1s core-level spectra of p-CoSi 1 N 3 @D is well divided into four peaks, including pyridinic N, CoN, pyrrolic N, and graphitic N (Figure S12, Supporting Information). [45][46][47][48][49][50] The pyrrolic N in binding energy of 400.0 eV served as the dominant chemical species. Most importantly, different from diatomite, only a weak peak located at 101 eV, which associated to the SiC bond, can be observed in the high-resolution Si 2p XPS spectra of p-CoSi 1 N 3 @D (Figure S13, Supporting Information).…”

“…The XANES curve of p-CoSi 1 N 3 @D (Figure 3a) shows a white line peak between that of Co foil and CoO, demonstrating that Co single atoms carried positive charges and their oxidation states are situated between 0 and +2. [47,52,53] The Fourier-transformed k 3 -weighted EXAFS curve of p-CoSi 1 N 3 @D displays one prominent peak at 1.31 Å, corresponding to CoN scanning path (Figure 3b). A shoulder peak at around 1.88 Å is consistent with the prediction of CoSi coordination in CoSi x N 4-x models (Figures S18a, S19a, S20a, and S21a, Supporting Information), revealing the successful coordination of Si atoms in CoN 4 moieties.…”

Ni-Doped Ordered Nanoporous Carbon Prepared from Chestnut Wood Tannins for the Removal and Photocatalytic Degradation of Methylene Blue

“…Although titanium dioxide is widely reported to be one of the best photocatalysts for environmental purification due to its great photo-oxidative properties [ 28 , 29 , 30 , 31 , 32 , 33 ], nickel oxide has also proved to be very efficient in this extent [ 34 , 35 , 36 ]. Thus, the latter is known to be a p-type semiconductor with a band gap of 3.5 eV that is stable, non-toxic, and has high photocatalytic activity [ 34 , 35 , 36 ].…”

“…Although titanium dioxide is widely reported to be one of the best photocatalysts for environmental purification due to its great photo-oxidative properties [ 28 , 29 , 30 , 31 , 32 , 33 ], nickel oxide has also proved to be very efficient in this extent [ 34 , 35 , 36 ]. Thus, the latter is known to be a p-type semiconductor with a band gap of 3.5 eV that is stable, non-toxic, and has high photocatalytic activity [ 34 , 35 , 36 ]. Overall, the process of photocatalytic degradation appears to be very attractive, as it involves the production of highly active radicals that can unsystematically and rapidly decompose a wide range of pollutants, resulting in the formation of harmless products such as carbon dioxide and water [ 26 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ].…”

“…Thus, the latter is known to be a p-type semiconductor with a band gap of 3.5 eV that is stable, non-toxic, and has high photocatalytic activity [ 34 , 35 , 36 ]. Overall, the process of photocatalytic degradation appears to be very attractive, as it involves the production of highly active radicals that can unsystematically and rapidly decompose a wide range of pollutants, resulting in the formation of harmless products such as carbon dioxide and water [ 26 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Several mechanisms for the photocatalytic degradation of dyes have been suggested in literature [ 26 , 29 , 30 , 31 , 32 , 33 , 36 ].…”