Design of Three-Dimensional Hollow-Sphere Architecture of Ti₃C₂T_x MXene with Graphitic Carbon Nitride Nanoshells for Efficient Photocatalytic Hydrogen Evolution

Abstract

Photocatalytic water splitting is the most environmentally friendly method to generate energy. Despite intense research in this area, rapid charge-carrier recombination and limited light absorption of semiconductor-based photocatalysts remain key challenges. Herein, protonated g-C 3 N 4 /Ti 3 C 2 T x MXene hollow spheres, fabricated by electrostatic layer-by layer assembly and a sacrificial template, were used for effective photocatalytic hydrogen (H 2 ) evolution. The constructed three-dimensional (3D) hollow spheres exhibited enhanced light absorption, a two-dimensional (2D) heterostructure to shorten the electron migration distance, a Schottky junction to facilitate separation and transfer of charge carriers, and high specific surface area for efficient H 2 adsorption. The optimal formulation had an H 2 production rate of 982.8 μmol g −1 h −1 , which is more than 3.5-fold higher than the H 2 production rate of pure protonated g-C 3 N 4 and 1.22-fold higher than the H 2 production rate of protonated g-C 3 N 4 /Ti 3 C 2 T x , which lacks the hollow structure. This unique 3D heterojunction structure made from 2D materials improved photocatalytic H 2 production performance and can be readily extended to other reactions. KEYWORDS: Ti 3 C 2 T x MXene, g-C 3 N 4 , photocatalytic water splitting, hydrogen evolution reaction, 3D architecture

Boosting Photocatalytic Activity Using Carbon Nitride Based 2D/2D van der Waals Heterojunctions

“…265 Modifications in MXene such as creating 3-D hollow morphological structure and oxygen vacancies (OV) are also done for superior performance. 266,267 For example, Tahir et al not only observed that the creation of oxygen vacant sites in MXene enhances the optical absorption and charge transportation but also found that, due to high electron conductivity, the synthesized material showed promising results for selective CO 2 methanation. 267 Other variations in MXene such as delamination (d-Ti 3 C 2 ) are performed to provide a homogeneous and uniform distribution while making composites with g-C 3 N 4 .…”

“…Besides, black phosphorus quantum dots (BQs) with high absorption coefficients, tunable band gap, high hole mobility, and excellent quantum confinement effects have also been employed alongside g-C 3 N 4 nanosheets. , However, MXene is used as an intermediate to fast track transmission of photogenerated charges and also to overcome the shortcomings of BQ/g-C 3 N 4 such as low interfacial contact and low charge carrier mobility . Modifications in MXene such as creating 3-D hollow morphological structure and oxygen vacancies (OV) are also done for superior performance. , For example, Tahir et al not only observed that the creation of oxygen vacant sites in MXene enhances the optical absorption and charge transportation but also found that, due to high electron conductivity, the synthesized material showed promising results for selective CO 2 methanation …”

In Situ Growth of ZnIn2S4 on MOF-Derived Ni–Fe LDH to Construct Ternary-Shelled Nanotubes for Efficient Photocatalytic Hydrogen Evolution

“…Hydrogen energy plays a crucial role in replacing traditional fossil fuels, owing to its high energy density and environmental friendliness . Sustainable hydrogen generated from photocatalytic water splitting has become a current hot topic, and numerous semiconductors have been reported, such as TiO 2 , ZnO, CdS, ZnIn 2 S 4 , carbon nitride, etc . − As one of the ternary metal chalcogenides, ZnIn 2 S 4 with a two-dimensional (2D) ultrathin layered structure and a moderate band gap of ∼2.48 eV possesses the advantages of a large surface area, a remarkable visible light response, and unique optical properties . Nevertheless, the photocatalytic hydrogen evolution of ZnIn 2 S 4 is limited by the rapid charge recombination .…”

Role of Ti3C2 MXene as Prominent Schottky Barriers in Driving Hydrogen Production through Photoinduced Water Splitting: A Comprehensive Review

“…78 Accordingly, Kang et al highlighted that the g-C 3 N 4 integrated with Ti 3 C 2 MXene hollow spheres profoundly generated 1.22-fold higher hydrogen than the intrinsic g-C 3 N 4 /Ti 3 C 2 MXene composite. 79 An improved photocatalytic activity was ascribed due to the hollow structure morphology enhancing the specific surface area from 77.4 to 100.1 m 2 g −1 , which aided in the reactant adsorption.…”