Photocatalytic performance of dual-function selenium-enriched biomass-derived activated carbon as a catalyst for dye degradation and hydrogen production

In this work, hemp-derived biochar (BC) was synthesized and then activated with KOH to achieve activated carbon (AC). The selenium (Se 1, 3, 5 wt%) was loaded over AC and characterized using various techniques to investigate the physicochemical, electrochemical, and photocatalytic performance for dye degradation and H₂ generation as dual function photocatalyst. BC, AC, and the influence of different loading of Se (1 wt%, 3 wt%, 5 wt%) were examined for the degradation of crystal violet (CV) dye under sunlight. Amongst 3% Se-AC showed the maximum degradation efficiency (98.2%) of CV dye within 75 min and the electrons (e⁻) had a major contribution to the degradation of CV during the active radical trap test. The photocatalytic H₂ production performance was tested and the maximum H₂ rate 3095 μmol/g/h and light to hydrogen efficiency (LTH) 2.36% were achieved for 3% Se-AC. The post-reaction characterization showed competitive stability. A possible reaction mechanism was proposed for photocatalytic H₂ production and it is suggested that the Se loading played a key role in charge transfer enhancement due to high polarizability, d-electron richness, and its bond energy with hydrogen atoms (Se-H_ads is 273 kJ/mol) is comparable to the platinum (Pt) (Pt-H_ads is 251 kJ/mol).