Mo<sub><i>x</i></sub>C Heterostructures as Efficient Cocatalysts in Robust Mo<sub><i>x</i></sub>C/g-C<sub>3</sub>N<sub>4</sub> Nanocomposites for Photocatalytic H<sub>2</sub> Production from Ethanol
Yan Wang, Arturo Pajares, Jarosław Serafin, Xavier Alcobé, Frank Güell, Narcı́s Homs, Pilar Ramı́rez de la Piscina
Abstract
High Resolution Image Download MS PowerPoint Slide In this work, we studied new materials free of noble metals that are active in photocatalytic H 2 generation from ethanol aqueous solutions (EtOH aq ), which can be obtained from biomass. Mo x C/g-C 3 N 4 photocatalysts containing hexagonal (hcp) Mo 2 C and/or cubic (fcc) MoC nanoparticles on g-C 3 N 4 nanosheets were prepared, characterized, and evaluated for photocatalytic hydrogen production from EtOH aq (25% v/v). Tailored Mo x C/g-C 3 N 4 nanocomposites with Mo x C crystallite sizes in the 4–37 nm range were prepared by treatment with ultrasound of dispersions containing Mo x C and g-C 3 N 4 nanosheets, formerly synthesized. The characterization of the resulting nanocomposites, Mo x C/g-C 3 N 4, by different techniques, including photoelectrochemical measurements, allowed us to relate the photocatalytic performance of materials with the characteristics of the Mo x C phase integrated onto g-C 3 N 4 . The samples containing smaller hcp Mo 2 C crystallites showed better photocatalytic performance. The most performant nanocomposite contained nanoparticles of both hcp Mo 2 C and fcc MoC and produced 27.9 mmol H 2 g –1 Mo; this sample showed the lowest recombination of photogenerated charges, the highest photocurrent response, and the lowest electron transfer resistance, which can be related to the presence of MoC-Mo 2 C heterojunctions. Moreover, this material allows for easy reusability. This work provides new insights for future research on noble-metal-free g-C 3 N 4 -based photocatalysts.