Metal-Oxide-Mediated Subtractive Manufacturing of Two-Dimensional Carbon Nitride for High-Efficiency and High-Yield Photocatalytic H₂ Evolution

Abstract

g-C 3 N 4 is a promising visible-light-driven photocatalyst for H 2 evolution reaction; however, the achievement of the high photocatalytic performance is primarily limited by the low separation efficiency of the photogenerated charge carriers and partly restricted by the slow kinetics of charge transfer. 2D g-C 3 N 4 can significantly improve the charge generation, transfer, and separation efficiencies. The 2D g-C 3 N 4 -based Z-scheme heterostructure can further enhance the charge-carrier separation and simultaneously increase the redox ability, thereby further boosting the photocatalytic performance. Here we report a transition-metal-oxide (TMO)-mediated subtractive manufacturing process toward the large-scale synthesis of 2D g-C 3 N 4 and the simultaneous formation of a 2D/2D TMO/g-C 3 N 4 Z-scheme heterojunction. The TMOs serve as catalysts to facilitate the hydrolysis reaction of the bulk g-C 3 N 4 in the presence of moist air, forming 2D g-C 3 N 4 . The resulting 2D/ 2D TMO/g-C 3 N 4 catalysts, in particular, 2D/2D Co 3 O 4 /g-C 3 N 4 , exhibit high-efficiency and high-yield photocatalytic H 2 evolution due to the suppression of electron−hole pair recombination and enhanced redox ability. The 2D/2D Co 3 O 4 /g-C 3 N 4 photocatalyzes the H 2 evolution with a rate of ∼370 μmol h −1 within λ > 400 nm. The external quantum efficiency of 2D/2D Co 3 O 4 /g-C 3 N 4 at λ = 405 nm reaches 53.6%, which is among the highest values for g-C 3 N 4 -based catalysts.

Construction of Hierarchical Hollow Co9S8/ZnIn2S4 Tubular Heterostructures for Highly Efficient Solar Energy Conversion and Environmental Remediation

“…Furthermore,t he sacrificial agent (TEOA) was rapidly consumed through oxidation by holes in the photocatalytic H 2 evolution reaction because of the high H 2 evolution rate. [18] Therefore,t he H 2 evolution rate slightly decreased after three cycles.However, the photocatalytic H 2 evolution rate was recovered when an additional 5mLo fT EOAwas added to the reaction system, indicating that the prepared Co 9 S 8 /ZnIn 2 S 4 heterostructures in this study possess good stability for H 2 evolution. The subsequent XRD and TEM measurements after the cycles further confirmed this finding.T he XRD pattern of the recycled photocatalyst, named 10 %-Co 9 S 8 /ZnIn 2 S 4 -AP,w as consistent with that of the initial sample,and the positions of the characteristic peaks did not obviously shift (Supporting Information, Figure S13a).…”

Short‐time Thermal Oxidation of Ultrathin and Broadband Carbon Nitride for Efficient Photocatalytic H2 Generation

“…In addition, UBCN retains the highly porous structure of BCN, which is not available for UCN, the highly porous structure can shorten the diffusion path for photogenerated carriers and enhance the absorption of reactants . According to the atomic force microscopy (AFM) images (Figure ), the measured thickness of Bulk CN is about 230 nm, and the thickness of UBCN is exfoliate to about 1.37 nm, revealing that UBCN has a ultrathin structure . The larger specific surface area and the abundant porous structure can be further validated by Nitrogen adsorption‐desorption isotherms and Pore size distribution curves.…”

“…[13] According to the atomic force microscopy (AFM) images (Figure 2), the measured thickness of Bulk CN is about 230 nm, and the thickness of UBCN is exfoliate to about 1.37 nm, revealing that UBCN has a ultrathin structure. [14] The larger specific surface area and the abundant porous structure can be further validated by Nitrogen adsorption-desorption isotherms and Pore size distribution curves. As shown in Figure S1a, the specific surface area of Bulk CN, BCN, UCN and UBCN are calculated to be 11.3, 23.7, 161.8 and 165.3 m 2 /g, respectively.…”

Construction of Hierarchical Hollow Co9S8/ZnIn2S4 Tubular Heterostructures for Highly Efficient Solar Energy Conversion and Environmental Remediation

“…The photostability of the optimal Co 9 S 8 /ZnIn 2 S 4 composite was evaluated through the photocatalytic H 2 evolution reaction in the presence of a prolonged visible‐light irradiation of 25 h, and the H 2 evolution rate for every 5 h reaction was calculated (Figure d). Furthermore, the sacrificial agent (TEOA) was rapidly consumed through oxidation by holes in the photocatalytic H 2 evolution reaction because of the high H 2 evolution rate . Therefore, the H 2 evolution rate slightly decreased after three cycles.…”