Photocatalytic materials are pivotal for the implementation of disruptive clean energy applications such as conversion of H₂O and CO₂ into fuels and chemicals driven by solar energy. However, efficient and cost-effective materials able to catalyze the chemical reactions of interest when exposed to visible light are scarce due to the stringent electronic conditions that they must satisfy. Chemical and nanostructuring approaches are capable of improving the catalytic performance of known photoactive compounds however the complexity of the synthesized nanomaterials and sophistication of the employed methods make systematic design of photocatalysts difficult. Here, we show by means of first-principles simulation methods that application of biaxial strain, η, on semiconductor oxide thin films can modify their optoelectronic and catalytic properties in a significant and predictable manner. In particular, we show that upon moderate tensile strains CeO₂ and TiO₂ thin films become suitable materials for photocatalytic conversion of H₂O into H₂ and CO₂ into CH₄ under sunlight. The band gap shifts induced by η are reproduced qualitatively by a simple analytical model that depends only on structural and dielectric susceptibility changes. Thus, epitaxial strain represents a promising route for methodical screening and rational design of photocatalytic materials.

光催化材料对于实施破坏性清洁能源应用（例如H ₂ O和CO _2的转化）至关重要。转化为太阳能驱动的燃料和化学物质。然而，由于必须满足严格的电子条件，因此在暴露于可见光时能够催化感兴趣的化学反应的有效且经济的材料稀缺。化学和纳米结构化方法能够改善已知光敏化合物的催化性能，但是合成纳米材料的复杂性和所用方法的复杂性使光催化剂的系统设计变得困难。在这里，我们通过第一性原理模拟方法表明，在半导体氧化物薄膜上应用双轴应变η可以显着且可预测的方式改变其光电和催化性能。特别是，我们表明在中等拉伸应变下CeO ₂TiO ₂薄膜成为在阳光下将H ₂ O光催化转化为H ₂和将CO ₂光转化为CH _4的合适材料。由η引起的带隙位移通过简单的分析模型定性地再现，该模型仅取决于结构和介电常数的变化。因此，外延应变代表了用于光催化材料的系统筛选和合理设计的有前途的途径。