RESUMO
Catalysts composed of nanocluster and single-atom (SA) were extensively used to enhance electrocatalytic water splitting performance, whereas study of their photocatalytic hydrogen (H2) evolution activity was limited. Herein, carbon nitride (CN) decorated by ruthenium (Ru) cocatalysts existed as SA + cluster, cluster + nanoparticles (NPs), and NPs were prepared by impregnation and calcination processes. The correlation between existential form, content of Ru cocatalyst and H2 evolution rate were carefully discussed. It was found that Ru NPs were favor for water molecule adsorption, whereas Ru SAs and clusters facilitated H2 desorption. Theoretical calculations revealed that Ru clusters + NPs cocatalyst were beneficial for H* intermediate formation. Water splitting tests found that 1.07 wt% Ru NPs + cluster modified CN showed the highest H2 evolution rate of 13.64 mmol h-1 g-1, which was 266.4 and 1.5 times higher than those of CN and Ru NPs (2.33 wt%) decorated CN, respectively. This work deeply reveals the influences of existential form of Ru cocatalysts on photocatalytic water splitting of CN, and provides thought in designing new cocatalysts to largely enhance H2 evolution.
RESUMO
In this study, nickel hydroxide (Ni(OH)2) was employed to modify potassium (K)-doped graphitic carbon nitride (g-C3N4, CN) for enhancing photocatalytic CO2 reduction. The light absorption and charge separation performances of CN were enhanced after modification. Experiments and theoretical calculations indicated that the loaded Ni(OH)2 could gather electrons, facilitate adsorption and activation of CO2. The optimized photocatalyst exhibited high CO2 reductive rate with CO and CH4 yields of 42.6 and 3.5 µmol g-1, respectively after 3 h irradiation in the presence of 0.5 mL water, which was 1.4 and 4.6 times higher than the yields on K-doped CN and Ni(OH)2-decorated CN, respectively. This work provides new thought for enhancing CO2 reductive performance of CN.