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Electron transpiration cooling (ETC) is a novel thermal protection technology developed based on the effect of thermal electron emission. The fundamental requirement for implementing ETC is to develop materials with both thermal protection and low work function properties. In this study, rare earth oxides were employed to modify the typical thermal protection material ZrB 2 -SiC, with the aim of reducing the work function of ZrB 2 -SiC. The work function of the material was meticulously evaluated using ultraviolet photoelectron spectroscopy (UPS). The phase composition and elemental composition of the materials were characterized using energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), respectively. The adjustment mechanism of rare earth oxides on the work function of the materials was analyzed. The results indicated that doping with rare earth oxides effectively reduced the work function of ZrB 2 -SiC by up to 0.59 eV. This reduction was attributed to the oxygen vacancies within the crystal structure of the rare earth oxides, which supplied valence electrons free from covalent bond constraints. These free electrons increased the electron density available for ZrB 2 -SiC, thereby enhancing the material's electron emission capability. This study offers a new class of candidate materials for ETC and provides technical support for the engineering application of ETC technology. • Rare earth oxide doping was used to reduce the work function of ZrB 2 -SiC heat-resistant materials. • The effects of two rare earth oxides and different doping contents on the work function of the materials were evaluated. • The mechanism through which rare earth oxide doping decreased the work function of ZrB 2 -SiC was revealed. • A new class of candidate materials for electron transpiration cooling technology was proposed. [ABSTRACT FROM AUTHOR]