Surface photovoltage spectrum(SPS), field-induced surface photovoltage spectrum(FISPS) and gas probe techniques are used together to study surface photovoltage(SPV) property of ZnO nanoparticles. The SPS of ZnO nanoparticles consists of two parts, band-to-band transition(P1,P2) and surface states transition(P3). The result shows that the SPV response is mostly attributed to the built-in field formed by active adsorbates, most of which is O 2. Competitive adsorption of O 2 and H 2O exists on ZnO surface. They play different roles in the influence on SPS. The Adsorption of O 2 weakens P3, whereas H 2O enhances P3. And the velocity of adsorption and desorption of O 2 on the surface is significantly faster than H 2O. The adsorption and desorption of H 2O may be correlated with the adjustment of surface structure.
