Partial reduction of CO2 by carbon to produce CO, i.e., the reverse Boudouard reaction, is potentially useful to CO2 utilization. In regards to this reaction, the existing alkaline metal carbonate and Ni-0 metal catalysts require special enhancements on interfacial contact between catalyst and carbon. The present research found miniature Ni-0 reactive sites coupled with boron oxide, released from in-situ degradation of nickel borate under the reaction condition. This catalyst system manifests a far higher gasification activity than Ni-0 reactive sites generated from the reduction of nickel oxide precursor. The study provides an insight into the characteristics of this gasification system. Furthermore, we also noticed that Gd(III) or Sm(III)-doped ceria can catalyze the reaction through a different mechanism from the Ni-0-based catalyst. The doped ceria catalytic systems unveil a pulse-like CO production pattern. Each pulse comes from one-off elimination of the oxy-groups on carbon surface, which is followed by a subsequent growth due to the oxygen transfer from CO2 through the mediating role of the doped ceria. (C) 2016 Elsevier B.V. All rights reserved.