Highly Conjugated Graphitic Carbon Nitride Nanofoam for Photocatalytic Hydrogen Evolution

Abstract

As a metal-free photocatalyst, graphitic carbon nitride (g-CN) shows great potential for photocatalytic water splitting, although its performance is significantly limited by structural defects due to incomplete polymerization. In the present work, we successfully synthesize highly conjugated g-CN nanofoam through an iodide substitution technique. The product possesses a high polymerization degree, low defect density, and large specific surface area; as a result, it achieves a hydrogen evolution rate of 9.06 mmol h–1 g–1 under visible light irradiation, with an apparent quantum efficiency (AQE) of 18.9% at 420 nm. Experimental analysis and theoretical calculations demonstrate that the recombination of photogenerated carriers at C–NH x defects was effectively depressed in the nanofoam, giving rise to the high photocatalytic activity.

Revisiting the roles of dopants in g-C3N4nanostructures for piezo-photocatalytic production of H2O2: a case study of selenium and sulfur

“…S2a,† N 2 adsorption–desorption plots of the prepared samples exhibit the type IV isotherm with an H3 hysteresis loop based on the Brunauer–Deming–Deming–Teller classification. 28,29 The porosities could be created due to the evaporation and decomposition of NH 4 Cl into HCl and NH 3 , evidenced by the results in Table S3 and Fig. S2b†.…”

Exploring the Remarkably High Photocatalytic Efficiency of Ultra-Thin Porous Graphitic Carbon Nitride Nanosheets

“…However, its practical applications are hindered because of its still limited absorption in the visible range, a high recombination rate of photogenerated charge carriers, and a low specific surface area caused by its bulk nature [ 42 , 43 , 44 ]. To address its shortcomings, numerous efforts have been made, including metal and non-metal doping [ 45 ], defect engineering [ 46 ], surface modification with other carbon-based nanomaterials [ 47 ], morphology modulation [ 48 ], and coupling with other lower-bandgap semiconductors [ 49 ]. Nevertheless, improving the photocatalytic performance of C 3 N 4 -based materials to a suitable level, without involving any expensive metals, has remained a significant challenge [ 50 , 51 ].…”

Matrix Doped C3N4 with Hierarchical Microstructures and High Vis–NIR Light Photoactivity

“…GCN (graphitic carbon nitride) is a candidate catalyst for photocatalytic CO 2 reduction due to its mild band gap value (2.7 eV) and availability. − But it absorbs mainly in the UV zone (λ < 420 nm) and rarely in the Vis–NIR zone. To enhance the light absorption of C 3 N 4 , approaches are employed to modify the electronic structures with metal and nonmetal dopants. , At the molecular level, light absorption depends on the valence band (VB) width of the catalyst .…”