Crystalline Carbon Nitride Nanosheets for Improved Visible-Light Hydrogen Evolution

Abstract

Nanosheets of a crystalline 2D carbon nitride were obtained by ionothermal synthesis of the layered bulk material poly(triazine imide), PTI, followed by one-step liquid exfoliation in water. Triazine-based nanosheets are 1-2 nm in height and afford chemically and colloidally stable suspensions under both basic and acidic conditions. We use solid-state NMR spectroscopy of isotopically enriched, restacked nanosheets as a tool to indirectly monitor the exfoliation process and carve out the chemical changes occurring upon exfoliation, as well as to determine the nanosheet thickness. PTI nanosheets show significantly enhanced visible-light driven photocatalytic activity toward hydrogen evolution compared to their bulk counterpart, which highlights the crucial role of morphology and surface area on the photocatalytic performance of carbon nitride materials.

Pore confinement effects and stabilization of carbon nitride oligomers in macroporous silica for photocatalytic hydrogen production

“…These include mesoporous, [35-37, 39-41, 45, 48, 86] nanocluster, [49,52] and nanosheet [42][43][44] if the porous walls of the mac-SiO2 support were heavily decorated with CN. However, CO2…”

“…With respect to morphology, the specific photocatalytic activity of carbon nitrides has been improved by increasing the surface area via the introduction of mesopores, [22,[35][36][37][38][39][40][41] nanosheet exfoliation, [42][43][44] and synthesis of morphologies containing a range of nano-to macroscopic structural features. [39,[45][46][47][48][49][50][51][52][53] The specific activity of these morphologies is typically increased by 3-10 fold compared to the bulk carbon nitride under visible light (≥ 400 nm) illumination.…”

A Solution‐Processable Polymer Photocatalyst for Hydrogen Evolution from Water

“…[13,14] After the potential of g-C 3 N 4 was first observed, while focusing on the hydrogen evolution half-reaction, interest has begun to shift to achieving overall water splitting using these materials. [15,16] However, the exact structure of most g-C 3 N 4 materials is unknown and the synthesis usually involves high temperature processing, which offers limited scope for fine-tuning structure and properties.…”

Carbon nitrides: synthesis and characterization of a new class of functional materials

“…Carbon nitride solid state compounds are emerging as important materials for energy and sustainability applications ranging from visible-UV light harvesting and photocatalysis, [1][2][3][4][5] to fuel cell and electrolyzer catalyst supports, [6][7][8] as redox catalysts, [9][10][11][12] as well as for other emerging areas. 5,[13][14][15][16][17][18] These applications all rely on the unique set of optical, electronic, and chemical properties possessed by the carbon nitrides, combined with their synthesis from readily available precursors, and their resistance to adverse chemical and physical environments.…”