Synergy of crystallinity modulation and intercalation engineering in carbon nitride for boosted H ₂ O ₂ photosynthesis

Abstract

Photosynthesis of hydrogen peroxide (H 2 O 2 ) by selective oxygen reduction is a green and cost-effective alternative to the energy-intensive anthraquinone process. Although inexpensive polymeric graphitic carbon nitride (g-C 3 N 4 ) exhibits the ability to produce H 2 O 2 , its disordered and amorphous structure leads to a high recombination rate of photogenerated carriers and hinders charge transfer between layers. Herein, we predict that stacked polymeric g-C 3 N 4 with ion intercalation (K + and I – ) can improve carrier separation and transfer by multiscale computational simulations. The electronic structures of g-C 3 N 4 were tailored and modified by intercalating K + and I – into the layer-by-layer structures. Guided by the computational predictions, we achieved efficient solar-driven H 2 O 2 production by employing this facile and ion-intercalated crystalline g-C 3 N 4 . An H 2 O 2 production rate of 13.1 mM g −1 h −1 and an apparent quantum yield of 23.6% at 400 nm were obtained. The synergistic effects of crystallinity regulation and dual interstitial doping engineering triggered the formation of new light absorption centers, the establishment of rapid charge diffusion channels, and the enhancement of two-electron oxygen reduction characteristics. This work sheds light on the dual tuning of crystallinity and electronic structure and broadens the design principles of organic-conjugated polymer photocatalysts for environmental remediation and energy conservation.

A Minireview: The Mechanism of H2O2 Photoproduction by Graphitic Carbon Nitride

“…Liu et al constructed K + /I − ‐intercalated g‐C 3 N 4 (CN‐KCl/KI) by molten salt method. [ 41 ] Compared with the pristine g‐C 3 N 4 (CN), CN‐KCl/KI has higher crystallinity (Figure 5b,d). The photoluminescence (PL) and time‐resolved photoluminescence (TRPL) spectra (Figure 5c,e) show that the PL peak is highly quenched and the average lifetime of the photogenerated charges excited by CN‐KCl/KI was prolonged from 2.65 to 4.44 ns after doping alkali metal.…”

“…Reproduced with permission. [ 41 ] Copyright 2023, National Academy Sciences. c) PL and e) TRPL spectra of CN and CN‐KCl/KI.…”

“…b) TEM and d) high-resolution TEM images of CN and CN-KCl/KI. Reproduced with permission [41]. Copyright 2023, National Academy Sciences.…”

Construction of a P, N Co-Doped Nanocarbon-Embedded g-C3N4 Hollow Sphere Nanoreactor for the Efficient Photocatalytic Production of Hydrogen Peroxide

“…As a promising chemical oxidant, hydrogen peroxide (H 2 O 2 ) has been widely employed in electronics, chemical synthesis, disinfection, and pollutant removal because of its low cost and high commercial value. − Currently, the traditional anthraquinone oxidation procedure is mainly used in the industrial production of H 2 O 2 , which requires large plants, high energy consumption, and generates huge amounts of waste. , To overcome these issues, substantial efforts have been made to develop alternative H 2 O 2 production methods with moderate reaction conditions and less detrimental environmental impacts. Most recently, the electrocatalytic approach based on heteroatom-doped carbon materials and photocatalytic technology with photo-activated metal-free materials for sustainable H 2 O 2 production through the O 2 reduction reaction (ORR) has received increasing attention. − Photocatalysis is generally considered a green process, with solar energy as the supply energy and oxygen and water as the raw resources. To achieve the efficient production of H 2 O 2 , it is vital to design and construct an effective photocatalytic system.…”

Boosting C3H6 Epoxidation via Tandem Photocatalytic H2O2 Production over Nitrogen-Vacancy Carbon Nitride

“…Photocatalytic O 2 reduction into H 2 O 2 (ORR) is considered a green, sustainable, and energy-saving method, in which alcohols are commonly used as sacrificial agents to increase H 2 O 2 production. − Disappointingly, difficult separation and purification limits further utilization of photogenerated H 2 O 2 . It is expected to construct a tandem system that combines ORR and HPPO processes with compatible solvent systems for efficient PO production using O 2 .…”