Polymeric Carbon Nitride with Localized Aluminum Coordination Sites as a Durable and Efficient Photocatalyst for Visible Light Utilization

Abstract

The development of efficient and yet economic photocatalysts that can utilize solar light is crucial for the sustainable future. We report a simple approach to introduce a bidentate type of metal coordination site in polymeric carbon nitride (PCN) by an in situ keto−enol cyclization route of acetylacetone and urea to incorporate a metal chelating pyrimidine derivative into the molecular framework of PCN. The resulting new metal coordination sites provide both N-and O-complexing ligands unlike the unmodified PCN that has Nligands only. As a proof-of-concept experiment, we introduced Al 3+ ions into these coordination sites, which induced significant enhancements in visible light photocatalytic activities for organic pollutant degradation and H 2 evolution as compared to those of bulk PCN and the conventional "nitrogen pot" metalcoordinated PCN. The optimized Al loading was as low as 0.32 wt %. The photocatalytic activities sensitively depended on the Al incorporation, and the Al-incorporated sample demonstrated an excellent stability in water with showing little sign of metal leaching. While the aluminum ions complexed in the nitrogen pot little influenced the photocatalytic activity, Al 3+ ions complexed by both N and O ligands in the alternative coordination sites significantly enhanced the photocatalytic activity of PCN. This study demonstrates a facile and scalable synthesis of PCN with alternative metal coordination sites for efficient solar energy conversion.

Remarkable Improvement in Photocatalytic Performance for Tannery Wastewater Processing via SnS2 Modified with N‐Doped Carbon Quantum Dots: Synthesis, Characterization, and 4‐Nitrophenol‐Aided Cr(VI) Photoreduction

“…Meanwhile, N 23 ‐CQDs loading could create a midgap state (sub‐bandgap) that allows catalysts to absorb lower energy photons than the actual optical bandgap and provides the localized energy levels for the photogenerated charge carriers. This can effectively suppress the recombination of the photogenerated charge carriers, resulting in a remarkable photocatalytic activity …”

Carbon Nitride Materials for Water Splitting Photoelectrochemical Cells

“…[59] Thel iquid-phase alternative involves the polymerization and condensation on the surface of the conductive substrate. [39] Successful methods of deposition of ex situ synthesized CN (always after an exfoliation step) include the application of electrophoretic deposition (EPD), [60] electrospinning (PVP/CN hybrid [61] or BiVO 4 /CN [6] ), and different casting techniques (spin-coat, [62] dip-coat, [63] doctor-blading, [64] and the like [65] ). Them ain difficulty of the casting methods is achieving af inal film that is both uniform and with good contact to the substrate.T his is hindered by the lateral variation of large aggregated CN particles leading to poor inter-particle contact as well as boundary defects.…”

Single Metal Atom Photocatalysis

“…As another promising photocatalyst, g‐C 3 N 4 possesses excellent visible light absorption, high stability, and capability to provide abundant N donor atoms to trap highly active metal atoms. Thus, it has been extensively explored as a support to anchor various metal atoms, including noble metal atoms (Pt, Pd, Ag) and nonprecious metal atoms (Al, Co). By a simple liquid‐phase reaction with g‐C 3 N 4 and H 2 PtCl 6 followed by annealing at a low temperature, Xie and co‐workers embedded single Pt atoms on the top of the five‐membered rings of the g‐C 3 N 4 network through PtC and PtN bonds .…”

“…Single nonprecious metal atoms, such as Al and Co, have also been successfully embedded on the surface of g‐C 3 N 4 . Cao et al constructed atomically dispersed Co atoms on g‐C 3 N 4 using the ALD method followed by O 3 treatment .…”