Abstract: Problem 6 of the 57th International Chemistry Olympiad addresses the resource utilization of carbon dioxide, establishing a comprehensive assessment framework that spans from thermodynamic fundamentals to cutting-edge energy chemistry. By incorporating two distinct technical approaches—thermochemical cycles and photocatalytic reduction—the problem systematically evaluates students' integrative understanding of chemical equilibrium, reaction kinetics, and semiconductor band theory. This paper presents a detailed solution to the problem while expanding upon relevant theoretical concepts to enhance readers' comprehension of competition-level chemistry questions.

Key words: International Chemistry Olympiad, Problem analysis, Photocatalytic reduction of CO₂, Physical chemistry, Inorganic chemistry