The photocatalytic dry reforming of methane (photoDRM: CH 4 + CO 2 = 2CO + 2H 2 ) converts greenhouse gases into valuable synthesis gas with photon energy. However, previous photoDRM catalysts comprising supported metal nanoparticles hardly avoid the recombination of photoexcited charges. Herein, we report that significant photoDRM performance can be achieved by a metal-oxide nanocomposite consisting of nanometer-thick, intertwined networks of fibrous rhodium metal and cerium dioxide, i.e., Rh#CeO 2 . The Rh#CeO 2 nanocomposite exhibits the world-highest conversion and yield in photoDRM under UV light irradiation, being accompanied with no other side reactions such as reverse water gas shift reaction. Theoretical simulations and Kelvin probe force microscopy demonstrate that the photoexcited electrons and holes in Rh#CeO 2 are efficiently partitioned into the Rh- and CeO 2 nanophases, respectively. The efficient charge partitioning in Rh#CeO 2 accounts for the selective photoDRM reaction. • Nano-architectural structure for efficient charge separation • Photocatalytic dry reforming of methane without external heater • Noble method to reduce greenhouse gas into chemical feedstock This research connects the science of nano-scale materials with the larger global problem of greenhouse gas recycling. Greenhouse gases, especially methane and carbon dioxide, are the most environmentally damaging gases, but their conversion has been done by thermal catalysis, so-called dry reforming under high temperatures of more than 800°C. In this paper, we highlight how we have achieved highly efficient conversion of greenhouse gases under non-heating conditions using light, a type of renewable energy, including sunlight. The working principle is photocatalysis, which uses electric charges generated by irradiating light on a semiconductor. The reason for the high efficiency is the creation of a structure in which nano-sized semiconductors and metals are intertwined with each other. From the viewpoint of materials science, the partitioning of charge distribution in the nanosize region was found to be the key to higher efficiency. Rh#CeO 2 , a nano-sized photocatalyst consisting of intertwined Rh and CeO 2 , is highly active and durable and has been successfully used to convert the worst greenhouse gases, CO 2 and CH 4 , into valuable syngas. The intertwined structure is very effective in partitioning the excited charges and maximizing the use of the interface as an active center.