Energy analysis on the water cycle consisting of photo catalyzing water splitting and hydrogen reacting with oxygen in a hydrogen fuel cell

[Display omitted] •Developing a novel cycle of hydrogen generation and combustion for energy analysis.•Discovering that the thermal temperature quotient (Q/T) is more than zero in the cycle.•Discovering that the value of “ΔS-Q/T” is less than zero in the cycle. Hydrogen fuel is a kind of clean energy that can be generated by photo catalyzing water splitting, and conversed into electric energy in high ratio by hydrogen fuel cells. The energy conversions in the cycle consisting of the two reactions are investigated through calculation and theoretical analysis, getting the results as following: the thermal temperature quotient (Q/T) is more than zero; and the value of “ΔS-Q/T” is less than zero in that cycle. The results are somewhat different to the traditional explanation of the Claudius principle and the expression of the second law of thermodynamic (ESLT).