Abstract Efficient ammonia decomposition is crucial for hydrogen economy, but inexpensive Ni catalysts require excessively high temperatures due to limited N-N coupling. Here, we overcome this challenge by constructing a photothermal catalyst with closely interfaced, defect-rich CeO 2-x nanodomains and electron-rich Ni nanoparticles on carbon nanotubes. The Ni-CeO 2-x /CNTs catalyst achieves a hydrogen production rate of 298.4 mmol g cat -1 min -1 under full-spectrum light irradiation, which exceeds that of most reported Ru catalysts, and maintained stable activity for over 50 h in continuous-flow operation. The high performance arises from the synergistic effect of thermally promoted photocatalytic N-H bond cleavage and a largely reduced N-N coupling barrier, enabled by efficient photothermal conversion of carbon nanotubes and the up-shifted d-band center of the Ce-Ov-Ni interface (Ov = oxygen vacancy).