Abstract (EN):
Citric acid-modified graphite-like carbon nitride materials (GCN-zCA) were synthetized by thermal copolymerization of dicyandiamide with different amounts of citric acid (z = between 5 and 25 mg). The resulting materials presented surface porosity, defective polymeric structure, and enhanced visible light absorption in the 450-700 nm range, attributed to the existence of mid-gap states and n-pi* electronic transitions. All the modified catalysts presented high selectivity (>99 %) towards the conversion of p-anisyl alcohol into p-anisaldehyde under visible-LED irradiation, the best performing photocatalyst (GCN-20CA) reaching 63 % yield (contrasting with 22 % obtained with bulk GCN) after 240 min reaction. GCN-20CA was also applied for hydrogen generation from water splitting. The modified material practically duplicated the hydrogen production when compared to bulk GCN (75 and 44 mu mol H-2 evolved in three hours, respectively), by using platinum nanoparticles as co-catalyst and EDTA as sacrificial electron donor. Moreover, p-anisyl alcohol was successfully used as sacrificial agent for water splitting, with simultaneous production of p-anisaldehyde and H-2. Reusability tests showed that GCN-20CA remained stable in a series of consecutive runs both for p-anisaldehyde synthesis and hydrogen production.
Idioma:
Inglês
Tipo (Avaliação Docente):
Científica
Nº de páginas:
10