posted on 2024-03-07, 14:08authored byYan Wang, Arturo Pajares, Jarosław Serafin, Xavier Alcobé, Frank Güell, Narcís Homs, Pilar Ramírez de la Piscina
In this work, we
studied new materials free of noble metals that
are active in photocatalytic H2 generation from ethanol
aqueous solutions (EtOHaq), which can be obtained from
biomass. MoxC/g-C3N4 photocatalysts containing hexagonal (hcp) Mo2C and/or
cubic (fcc) MoC nanoparticles on g-C3N4 nanosheets
were prepared, characterized, and evaluated for photocatalytic hydrogen
production from EtOHaq (25% v/v). Tailored MoxC/g-C3N4 nanocomposites with
MoxC crystallite sizes in the 4–37
nm range were prepared by treatment with ultrasound of dispersions
containing MoxC and g-C3N4 nanosheets, formerly synthesized. The characterization of
the resulting nanocomposites, MoxC/g-C3N4, by different techniques, including photoelectrochemical
measurements, allowed us to relate the photocatalytic performance
of materials with the characteristics of the MoxC phase integrated onto g-C3N4. The samples
containing smaller hcp Mo2C crystallites showed better
photocatalytic performance. The most performant nanocomposite contained
nanoparticles of both hcp Mo2C and fcc MoC and produced
27.9 mmol H2 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-Mo2C heterojunctions. Moreover,
this material allows for easy reusability. This work provides new
insights for future research on noble-metal-free g-C3N4-based photocatalysts.