Lattice-Matched CoP/CoS₂ Heterostructure Cocatalyst to Boost Photocatalytic H₂ Generation

Abstract

Transition-metal phosphides and sulfides are considered as promising cocatalysts for the photocatalytic hydrogen evolution reaction (HER), and the cocatalytic effect can be improved by directed heterostructure engineering. In this study, a novel lattice-matched CoP/CoS 2 heterostructure having a nanosheet morphology was developed as an HER cocatalyst and integrated in situ onto graphitic carbon nitride (g-C 3 N 4 ) nanosheets via a successive phosphorization and vulcanization route. First-principles density functional theory calculations evidenced that the construction of the lattice-matched CoP/CoS 2 heterostructure resulted in the redistribution of interface electrons, enhanced metallic characteristics, and improved H* adsorption. As a result of these effects, the CoP/CoS 2 heterostructure cocatalyst formed a 2D/2D Schottky junction with the g-C 3 N 4 nanosheets, thus promoting photoelectron transfer to CoP/CoS 2 and realizing fast charge-carrier separation and good HER activity. As expected, the CoP/CoS 2 heterostructure exhibited excellent cocatalytic activity, and the optimal loading of the cocatalyst on g-C 3 N 4 enhanced its HER activity to 3.78 mmol g −1 h −1 . This work furnishes a new perspective for the development of highly active noble-metal-free cocatalysts via heterostructure engineering for water splitting applications.

Improved H-adsorption ability and conductivity of a Co-doped Mo2N cocatalyst for efficient photocatalytic H2 generation of g-C3N4

“…The excellent electronic conductivity of Mo 2 N, Co–Mo 2 N and Cu–Mo 2 N endows them with the promoted photogenerated charge migration as high-performance cocatalysts for the HER. 27…”

“…Meanwhile, the DOS intensities of doped samples were enhanced by metal-atom doping. The excellent electronic conductivity of Mo 2 N, Co-Mo 2 N and Cu-Mo 2 N endows them with the promoted photogenerated charge migration as high-performance cocatalysts for the HER 27. XRD characterization and Fourier transform infrared spectroscopy (FT-IR) were performed over the prepared Mo 2 N/ g-C 3 N 4 , Cu-Mo 2 N/g-C 3 N 4 and Co-Mo 2 N/g-C 3 N 4 to study their crystal structure and surface functional groups.…”

Review on the Application of Semiconductor Heterostructures in Photocatalytic Hydrogen Evolution: State-of-the-Art and Outlook

“…A single semiconductor as a photocatalyst possesses numerous disadvantages such as a large band gap, narrow absorption spectral response, high electron–hole recombination rate, and difficult carrier separation, which make it difficult to exhibit a high photocatalytic activity for hydrogen production. Designing multiple semiconductors to form heterojunctions can compensate for the shortcomings of pure semiconductors and create synergistic effects in semiconductor composites by combining the excellent properties of each semiconductor. − The compound semiconductor has superior photocatalytic activity, which greatly enhances the rate and amount of hydrogen evolution. Semiconductor–semiconductor heterojunctions are often classified as cross-gap (Type I), interleaved-gap (Type II), and gap (Type III). , The more effective type II heterojunctions are mainly p–n-type heterojunctions, which results in forming an internal electric field at the interface, thus promoting the effective separation of photogenerated electrons and holes. − The n–n (p–p)-type heterojunctions drive the transfer of photogenerated carriers based on the valence and CB positions of the catalyst itself. − It has been found that Z-type heterojunctions could boost light trapping ability by the means of inhibiting photogenerated electron and hole recombination and promoting surface catalytic reactions.…”

Deciphering the photocatalytic hydrogen generation process of Fresnoite Ba2TiGe2O8 by electronic structure and bond analyses

“…Semiconductor photocatalysis has been a hot topic for decades since the first report on photocatalytic water splitting for TiO 2 , 1 and many efforts have been made to understand the photocatalytic mechanism, develop new catalysts, and improve catalytic efficiency, respectively. [2][3][4][5][6][7] Photocatalysis becomes more and more important both in environmental protection through photo-driven degradation of organic pollutants and in solving the energy crisis by photocatalytic hydrogen generation from water. 8,9 To date, a great number of semiconductors have been studied as well as their combinations to form composites, which are beneficial for enhancing the light harvesting ability or decreasing the recombination rate of photo-excitons, thus achieving a high efficiency.…”