Abstract
Hydrogen generation by water splitting is reported in nano-ZrO2+H2Oabs. and nano-ZrO2+H2Oflu. systems using gamma radiation at different ZrO2 particle sizes (50–70 nm) and temperatures (300–673K). The rates of molecular hydrogen (H2) formation in radiolysis process were studied in radiation-chemical process using γ-quanta (60Co, D = 0.26–0.22 Gy/s, T = 300–673K, 50–70 nm) with mZrO2 = 3 × 10−2 g, 0.5 mL water. The energy yield of molecular hydrogen in radiation-heterogeneous processes in both nano-ZrO2+H2Oabs. and nano-ZrO2+H2Oflu. systems increased as the particle size of nano-ZrO2 decreased. The temperature stimulated the process of heterogeneous radiolysis during radiation-heterogeneous processes in n-ZrО2+Н2Оabs. system in the range of 300–673K. The molecular hydrogen (H2) yield increased linearly with temperature from 1.57 to 19.6 molecules/100 eV for d = 50–70 nm of particle size. The contributions of thermal and radiation-thermal processes to the accumulation of molecular hydrogen (H2) in the contact of n-ZrO2 with water was revealed [1.57–19.6 molecules/100eV(50–70 nm)] and the activation energy of the processes of molecular hydrogen formation was 21.2 kJ/mol (50–70 nm) radiation-thermal processes and 28.8 (50–70 nm) kJ/mol thermal processes. Briefly, molecular hydrogen contents in the nano-ZrO2+H2Oflu. system; where nano-ZrO2 was in a water-soluble state, and the yield of molecular hydrogen for gamma rays (molecule/100eV) absorbed by 100 eV absorption; was 6.0–6.5 (50–70 nm) times higher than the n-ZrO2+H2Oabs. system. These results are promising for molecular hydrogen generation by water splitting in near future.
•Kinetics of molecular hydrogen generation in γ-radiolysis of water on n-ZrО2 surface.•Effect of the particle size and temperature on water splitting for hydrogen generation.•Determination of activation energy of molecular hydrogen formation.•Method may be used to generate green fuel hydrogen by water splitting.