<p>The photon-mediated conversion of CH₄ and CO₂ represents a green and sustainable route for producing transportation fuels and chemicals. Here we report an innovative, catalyst-free strategy for the conversion, by light, of CH₄ and CO₂ into CO/H₂ and C₂H₆. High-energy photons with a wavelength of 185 nm were found to initiate the reaction, and the additional use of photons with different energies at longer wavelengths further improved the reaction efficiency. In particular, the combination of 185-nm and 200–1,100-nm photons enabled CO, H₂ and C₂H₆ production rates of 3.1 mmol m⁻³ h⁻¹, 1.93 mmol m⁻³ h⁻¹ and 2.53 mmol m⁻³ h⁻¹, respectively. Moderate addition of H₂O was found to aid the reaction considerably. Moreover, a total gas conversion of 1.51% (24 h) was achieved in experiments simulating an oxygen-free environment. This work opens up a promising route for producing fuels and chemicals using CH₄ and CO₂ without the use of any catalysts, under ambient conditions.</p>