Improving the kinetics of O₂ reduction on oxide surfaces is critical in many energy and fuel conversion technologies. Here we show that the acidity scale for binary oxides is a powerful descriptor for tuning and predicting oxygen surface exchange kinetics on mixed conducting oxides. By infiltrating a selection of binary oxides from strongly basic (Li₂O) to strongly acidic (SiO₂) onto the surface of Pr_0.1Ce_0.9O_2-δ samples, it was possible to vary the chemical surface exchange coefficient k_chem by 6 orders of magnitude, with basic oxides such as Li₂O increasing k_chem by nearly 1,000 times, with surface concentrations as low as 50 ppm impacting k_chem. Strikingly, although the pre-exponential of k_chem scales linearly with the acidity of the infiltrated binary oxide, there is nearly no change in the activation energy. The origin of these dramatic changes is proposed to arise from the systematic increase in electron concentration at the Pr_0.1Ce_0.9O_2-δ surface with the decreasing acidity of the infiltrated binary oxide.

在许多能源和燃料转换技术中，改善氧化物表面的O ₂还原动力学至关重要。在这里，我们表明二元氧化物的酸度等级是调节和预测混合导电氧化物上的氧表面交换动力学的有力描述符。通过将二元氧化物的选择从强碱性（Li ₂ O）到强酸性（SiO ₂）渗透到Pr _0.1 Ce _0.9 O2 _-δ样品的表面，可以将化学表面交换系数k _chem改变6。数量级，碱性氧化物（例如Li ₂ O）增加k _chem几乎是1000倍，表面浓度低至50 ppm会影响k _chem。令人惊讶的是，尽管k _chem的预指数随渗透的二氧化物的酸度线性变化，但活化能几乎没有变化。提出这些剧烈变化的起因是由于渗透的二元氧化物的酸性降低，Pr _0.1 Ce _0.9 O2 _-δ表面电子浓度的系统增加。