Photocatalytic Hydrogen Production: Role of Sacrificial Reagents on the Activity of Oxide, Carbon, and Sulfide Catalysts

Abstract

Photocatalytic water splitting is a sustainable technology for the production of clean fuel in terms of hydrogen (H2). In the present study, hydrogen (H2) production efficiency of three promising photocatalysts (titania (TiO2-P25), graphitic carbon nitride (g-C3N4), and cadmium sulfide (CdS)) was evaluated in detail using various sacrificial agents. The effect of most commonly used sacrificial agents in the recent years, such as methanol, ethanol, isopropanol, ethylene glycol, glycerol, lactic acid, glucose, sodium sulfide, sodium sulfite, sodium sulfide/sodium sulfite mixture, and triethanolamine, were evaluated on TiO2-P25, g-C3N4, and CdS. H2 production experiments were carried out under simulated solar light irradiation in an immersion type photo-reactor. All the experiments were performed without any noble metal co-catalyst. Moreover, photolysis experiments were executed to study the H2 generation in the absence of a catalyst. The results were discussed specifically in terms of chemical reactions, pH of the reaction medium, hydroxyl groups, alpha hydrogen, and carbon chain length of sacrificial agents. The results revealed that glucose and glycerol are the most suitable sacrificial agents for an oxide photocatalyst. Triethanolamine is the ideal sacrificial agent for carbon and sulfide photocatalyst. A remarkable amount of H2 was produced from the photolysis of sodium sulfide and sodium sulfide/sodium sulfite mixture without any photocatalyst. The findings of this study would be highly beneficial for the selection of sacrificial agents for a particular photocatalyst.

CuCo2S4 Deposited on TiO2: Controlling the pH Value Boosts Photocatalytic Hydrogen Evolution

“…A comparison of the catalytic activity of materials is not straightforward due to the differing experimental setups, the different numbers reported for the activity, and the sacrificial agents applied. The effect of the latter was recently summarized in a review, showing that the catalytic activity of pure P25® strongly depends on the sacrificial agents . The highest activity was observed for TiO 2 /ethylene glycol (190.2 µmol H 2 in 6 h) and the lowest for lactic acid (27.6 µmol in 6 h), while TiO 2 /TEOA produced a low amount of 61.8 µmol H 2 in 6 h. Keeping all the difficulties in mind, we compare the performances of selected catalytic systems in Table to give the reader an impression about the activity of CCS10.…”

“…The effect of the latter was recently summarized in a review, showing that the catalytic activity of pure P25® strongly depends on the sacrificial agents. [74] The highest activity was observed for TiO 2 /ethylene glycol (190.2 μmol H 2 in 6 h) and the lowest for lactic acid (27.6 μmol in 6 h), while TiO 2 / TEOA produced a low amount of 61.8 μmol H 2 in 6 h. Keeping all the difficulties in mind, we compare the performances of selected catalytic systems in Table 2 to give the reader an impression about the activity of CCS10. As can be seen from the data, CCS10 and CCS20 show a far higher activity for H 2 evolution compared to other catalysts under comparable conditions (300 W Xe arc lamp and triethanolamine as sacrificial agent).…”

Photocatalytic hydrogen evolution from biomass conversion

“…As shown in Fig. 6 , Au 3+ can be easily reduced to Au 0 by the photogenerated electrons from photoexcitation of Au/CdS compared to the reduction of H + to H 2 [ 8 , 47 ]. These self-reduced Au nanoparticles can increase the charge transfer leading to better separation of electron–hole pairs.…”

Hollow Structured Metal Sulfides for Photocatalytic Hydrogen Generation

“…Amines and sulfide/sulfite can strongly bind to the surface of MS photocatalysts and efficiently scavenge VB holes than other sacrificial reagent molecules. Therefore, triethanolamine and Na 2 S/Na 2 SO 3 give enhanced H 2 generation as compared to sacrificial reagents of alcohol, organic acid, and sugar . The redox potential of the e − is determined by the CB edge of the MS used as the photocatalyst.…”