CO2-free hydrogen production from solar-driven photothermal catalytic decomposition of methane

Abstract

CO₂-free H₂ refers to H₂ production process without CO₂ emission, which is a promising clean energy in the future. Catalytic decomposition of methane (CDM) is a competitive technology to produce CO₂-free H₂ with large-scale. However, CDM reaction is highly endothermic and is kinetically and thermodynamically unfavorable, which typically requires a harsh reaction temperature above 800 °C. In this work, solar-driven photothermal catalytic decomposition of methane was firstly introduced to produce CO₂-free H₂ relying solely on solar energy as the driving force. A high H₂ yield of 204.6 mmol g^–1 h^–1 was observed over Ni-CeO₂ interface under photothermal conditions, along with above 87% reduction in the apparent activation energy (11.2 vs. 87.3 kJ mol^–1) when comparing with the traditional thermal catalysis. Further studies suggested that Ni/CeO₂ catalyst enhanced optical absorption in visible-infrared region to ensure the heat energy for methane decomposition. The generated electrons and holes participated in the redox process of photo-driven CDM reaction with enhanced separation ability of hot carriers excited by ultraviolet-visible light, which lowered activation energy and improved the photothermal catalytic activity. This work provides a promising photothermal catalytic strategy to produce CO₂-free H₂ under mild conditions.