Two‐photon Absorption in a Defect‐engineered Carbon Nitride Polymer Drives Red‐light Photocatalysis

Abstract

Exploiting photocatalysts that harvest the solar spectrum as broadly as possible remains a high‐priority target, but is a grand challenge. Herein, for the first time, we found that bulky polymer carbon nitride (denoted as PCN) possessed excellent two‐photon absorption behavior and confirmed that the bulky PCN can efficiently drive red‐light photocatalysis by two‐photon absorption processes. Long‐wavelength‐excited fluorescence measurements and confocal laser scanning microscopy clearly revealed the existence of two‐photon absorption in PCN. Moreover, we created nitrogen vacancies on the PCN surface by increasing the polymerization temperature and confirmed the nitrogen vacancies can efficiency accelerate charge separation. As a result, bulky PCN with nitrogen vacancies showed unexpected pollutant degradation and water splitting activity under 660 nm. Additionally, PCN obtained from other precursors also exhibited competent red‐light photocatalytic performance. This work represents an important step toward developing two‐photon‐absorption PCN photocatalysts for wide solar‐spectrum utilization.

Metal-Free C60-Doped Mesoporous Carbon Nitride Drives Red-Light Photocatalysis

“…Benzoquinone (BQ), disodium ethylenediamine tetraacetate (EDTA-2Na), and tertiary butanol ( t -BuOH) were chosen as the trapping agents for the superoxide radical (O 2 – • ), hole (h + ), and hydroxyl radical ( • OH), respectively. This selection aimed to discern the primary active species involved in the process . As depicted in Figure , the introduction of EDTA-2Na into the RhB solution resulted in a nearly unaltered degradation efficiency for mpg-CN–0.3C 60 .…”

“…This selection aimed to discern the primary active species involved in the process. 49 As depicted in Figure 11, the introduction of EDTA-2Na into the RhB solution resulted in a nearly unaltered degradation efficiency for mpg-CN−0.3C 60 . This observation implies that the hole (h + ) had a nonessential role in the degradation process.…”

Ultrathin Sulfur‐Doped g‐C3N4 Nanosheets Controlled by Steam Activation for Enhanced Visible‐Light Photocatalytic Performance

“…In this context, photocatalytic materials have attracted intense research attention for the direct absorption and utilization of visible light. Specifically, photocatalysts convert luminous energy into chemical power and generate active substances with strong oxidation ability, such as superoxide radicals ( * O 2À ), hydroxyl radicals ( * OH), electrons (e À ), and holes (h + ) via photochemical reactions, thus finding application in important processes such as photocatalytic water splitting to obtain H 2 as a clean energy source, [1][2] degradation of organic pollutants, [3][4][5] and elimination of Escherichia coli and Staphylococcus aureus. [6][7][8] In particular, the photocatalytic degradation technology is often used in the treatment of polluted wastewater based on using solar power to activate the photocatalyst, produce reactive oxygen species, change the internal structure of pollutants, and ultimately transform organic pollutants into CO 2 , H 2 O, or other green small molecules that can be naturally degraded.…”

Photocatalytic Air Purification Using Functional Polymeric Carbon Nitrides

“…[ 67 , 89 ] 3) The redshift of light absorption of the PCN can provide more chances to absorb photons and participate in the visible‐light‐driven heterogeneous catalysis of air purification. [ 90 , 91 , 92 , 93 ] 4) The high physicochemical/mechanical/chemical/thermal stabilities (attributed to its aromatic C–N heterocycles) of the PCNs reduce the inactivation and photo corrosion, thereby extending the life of the photocatalysts. [ 94 , 95 , 96 , 97 , 98 ] 5) A similar layered structure with graphite for PCN provides a large reaction space, improves gas absorption/desorption, and shortens the transmission distance of photogenerated charges.…”