Chiba University researchers achieve record CO2-to-methane conversion by balancing light and heat pathways

Japanese researchers clarify how light and heat work together in catalysts to convert CO2 into methane at record-breaking speeds.

By: AXL Media

Published: Apr 16, 2026, 8:00 AM EDT

Source: Information for this report was sourced from Chiba University

The Quest for a Functional Carbon Cycle

With global carbon dioxide emissions reaching a record 37.8 gigatons in 2024, the scientific community is intensifying efforts to transform this greenhouse gas into a valuable energy resource. Researchers at Chiba University have made a significant stride in this field by developing a method to convert CO2 into methane using sunlight and specialized catalysts. While the concept of photocatalytic reduction has existed for years, its practical application has been hindered by low efficiency and a lack of clarity regarding how light actually drives the reaction. Professor Yasuo Izumi, who led the study published in the Journal of the American Chemical Society, notes that identifying the true reaction pathways is essential for overcoming these industrial bottlenecks.

Distinguishing Between Light and Thermal Drivers

The central challenge in light-driven chemistry is determining whether a reaction is powered by true photocatalysis, involving light-induced electron excitation, or by the photothermal effect, where light simply generates heat. To solve this, the Chiba team tested Ru–Ni–ZrO2 and Ni–ZrO2 catalysts under varying light intensities while strictly controlling the surrounding temperature. By using a cooling bath to maintain the system at 295 K, they were able to isolate the photocatalytic effects from the heat-driven ones. Their results showed that when cooling was absent, photothermal effects became dominant, allowing the ruthenium-nickel catalyst to convert CO2 more than 2.7 times faster than its pure nickel counterpart.

The Role of Active Sites and Activation Energy

The study revealed that the chemical architecture of the Ru–Ni catalyst significantly lowers the energy barrier for fuel production. On these active sites, CO2 is adsorbed and dissociated into carbon monoxide and oxygen atoms with an activation energy of just 0.45 eV. This is substantially lower than the 0.79 eV required when using nickel alone. This energetic modulation allows for a more efficient breakdown of the CO2 molecule, which is notoriously stable and difficult to split. The researchers found that under intense irradiation, localized "hotspots" form on the nickel surfaces, where temperatures can surge to 126 °C, further accelerating the formation of methane beyond what simple ambient heating would allow.