Plasmonic Graphene-Like Au/C₃N₄ Nanosheets with Barrier-Free Interface for Photocatalytically Sustainable Evolution of Active Oxygen Species

Abstract

Graphene-like carbon nitride supported plasmonic Au NPs with physical barrier-free interface (Au/C3N4) were in situ synthesized by one-step polymerization of the homogeneous mixture of HAuCl4 and urea. The plasmonic graphene-like structure of Au/C3N4 with the physical barrier-free interface enhances the visible-light capturing capability, increases the redox potentials, and facilitates the directional transfer of electrons from N 2p of C3–N species in g-C3N4 to Au in the photocatalytic procedure, which greatly promotes the activity of Au/C3N4 for the evolution of •O2 –, •OH, and H2O2 species. The optimal Au/C3N4 sample provides the highest photocatalytic efficiency of active oxygen species, obtaining 31 (•OH), 68 (•O2 –), and 990 μmol L–1 h–1 (H2O2) without scavenger under visible light, respectively. The work supplies a new approach to design efficient graphene-like structures with a physical barrier-free interface for photocatalytically enhancing sustainable solar conversion.

S‐Scheme Photocatalytic Systems

“…[ 74 ] In photocatalytic process, O 2 molecular is activated and reduced into ·O 2 − with e − , and H 2 O is oxidized into ·OH and/or H 2 O 2 with h + . [ 75 ] In addition to the low efficiencies of e − and h + separation and migration as well as utilization, it is relatively difficult to satisfy thermodynamical conditions for reduction potentials of O 2 /·O 2 − (−0.33 V), O 2 /H 2 O 2 (0.69 V), and oxidation potential of H 2 O/·OH (1.99 V) in photocatalytic process. S‐scheme photocatalysts demonstrate efficient performances for reactive oxygen species (ROS) evolution in pollutant decomposition and sterilization processes, e.g., CoFe 2 O 4 /g‐C 3 N 4 , 0D/2D CeO 2 /g‐C 3 N 4 , S‐pCN/WO 2.72 , Sb 2 WO 6 /g‐C 3 N 4 , OVs‐Bi 2 O 3 /Bi 2 SiO 5 , In 2 O 3– x (OH) y /Bi 2 MoO 6 , and BP/BiOBr, Bi 2 MoO 6 /CdS, BiOCl/CuBi 2 O 4 , Bi 2 WO 6 /g‐C 3 N 4 , SnNb 2 O 6 /Ag 3 VO 4 , BiOBr/BiOAC 1–– x Br x , BiOI/Bi 2 WO 6 , Bi 2 O 3 /TiO 2 , In 2 S 3 /Bi 2 O 2 CO 3 , ZnO–V 2 O 5 –WO 3 , S‐doped g‐C 3 N 4 /TiO 2 , BiVO 4 /Ag 3 VO 4 , CdS/UiO‐66, α‐Fe 2 O 3 /Bi 2 WO 6 , Cd 0.5 Zn 0.5 S/g‐C 3 N 4 , Sb 2 WO 6 /BiOBr, and Bi 2 MoO 6 /g‐C 3 N 4 /Au.…”

“…À with e À , and H 2 O is oxidized into •OH and/or H 2 O 2 with h þ . [75] In addition to the low efficiencies of e À and h þ separation and migration as well as utilization, it is relatively difficult to satisfy thermodynamical conditions for reduction potentials of [28, Li et al utilized thin black phosphorus (BP) to couple BiOBr nanosheets to construct S-scheme BP/BiOBr nanoheterojunction for H 2 O 2 evolution, [80] as shown in Figure 10a. H 2 O 2 evolution rate over 10BP/BiOBr is 2.6 times SNO/CdS-D [31] λ > 420 nm 7808 -MCF-2 [49] λ > 420 nm 547.5 1.83 CZS/40Co 9 S 8 [50] λ > 420 nm 19 570 -CAM-5 [51] λ > 420 nm 17.1 -100%g-CN/BMO [34] λ > 420 nm 5.63 0.63 NMS/SCN [29] λ > 300 nm 658.5 -TiO 2 /In 0.5 WO 3 [53] λ > 350 nm 132.6 15.6 CCN0.1 [54] λ > 420 nm 758.8 1.17 0.5-MoO 3 /g-C 3 N 4 [55] λ > 420 nm 512.5 g-C 3 N 4 /Zn 0.2 Cd 0.8 S [56] λ > 420 nm 6690 -MC-15 [30] Visible light 7440 14.3…”

Antibacterial and ultraviolet protective neodymium-doped TiO2 film coated on polypropylene nonwoven fabric via a sputtering method

“…Electrons (e − ) reduce O 2 to superoxide radicals −O 2 − , and holes (h + ) oxidize H 2 O molecules to highly active hydroxyl radicals −OH − , −OOH − , etc. 22 These free radicals can oxidize most organic matter and inorganic pollutants because of their strong oxidizing ability. They can penetrate the cell membrane and destroy the membrane structure, then decompose cells, viruses, and molds, and convert them into small inorganic molecules, that is, CO 2 , N 2 , and H 2 O and other harmless substances.…”

The embedded CuInS2 into hollow-concave carbon nitride for photocatalytic H2O splitting into H2 with S-scheme principle

“…The former requires significant photon energy to excite photogenerated charges; however, this requirement cannot be met. The second factor dynamically reflects a competition in the utilization of the photogenerated charge, and etransfers to H2O slowly (~μs); however, erecombines with h + rapidly (~ps) [6,7]. Although there are many strategies to be attempted [8,9], such as the heteroatom doping, heterojunction construction, and plasmonic noble metal loading, it is still difficult to integrate the electricity and optics of semiconductors to simultaneously satisfy the thermodynamic and dynamic requirements of photogenerated carriers.…”