Surface-frustrated Lewis pairs are unique catalytic sites formed by the combination of Lewis acid and Lewis base sites locked in close proximity on the material's surface. These pairs are particularly effective in accelerating catalytic conversions due to their collective ability to simultaneously accept and donate electrons, thereby facilitating bond breaking and formation. The team synthesized a series of isomorphic B-site-substituted LaMn_1−xCu_xO₃ perovskite catalysts. Notably, partial substitution of Mn(IV) with Cu(II) in LaMn_1−xCu_xO₃ increases the proportion of Mn(III) sites and leads to the emergence of oxygen vacancies and surface hydroxyl groups. This oxygen non-stoichiometry provides the necessary redox-active Lewis acid (Mn(IV)/Mn(III)) and Lewis base (O(-II) and OH(-I)) sites for surface-frustrated Lewis pairs formation. Among all the catalysts, the LaMn_0.9Cu_0.1O₃ delivered the highest photocatalytic activity, achieving an ethylene production rate of 1.1 mmol g^–1 h^–1 and ethane conversion of 4.9%.

To elucidate the reaction pathway and the role of surface-frustrated Lewis pairs in facilitating C–H activation, the researchers probed ethane adsorption behaviour and Mn–H bond formation using in situ diffuse reflectance infrared Fourier transform spectroscopy, solid-state magic-angle spinning proton nuclear magnetic resonance, and density functional theory modelling. In the first C–H activation stage, a hydrogen from ethane bonds to a Lewis base oxygen or hydroxide site, forming Mn–OH or Mn–OH₂ (pictured). Simultaneously, Mn–C₂H₅ forms at the Lewis acid sites. During the second step, a β-hydrogen of the anchored ethyl group is further activated by a Mn site to generate Mn–H species, followed by ethylene desorption and regeneration of the active sites. Under illumination, photogenerated electrons and holes are assumed to localize at the Lewis acid and Lewis base sites, respectively. This localization enhances the interaction between reactants and active sites, thereby minimizing the activation barriers. Additionally, as in other photothermal processes, local heat caused by irradiation further accelerates the reaction. This study provides a compelling demonstration of the applicability of the surface-frustrated Lewis pairs engineering strategy in developing efficient photocatalysts for activating stable molecules.

表面受阻路易斯对是由紧密靠近材料表面的路易斯酸和路易斯碱位点组合形成的独特催化位点。这些对在加速催化转化方面特别有效，因为它们具有同时接受和给予电子的集体能力，从而促进键的断裂和形成。该团队合成了一系列同构B位取代的LaMn _{1− x} Cu _x O ₃钙钛矿催化剂。值得注意的是，LaMn _{1− x} Cu _x O ₃中Mn(IV)被Cu(II)部分取代增加了Mn(III)位点的比例，并导致氧空位和表面羟基的出现。这种氧非化学计量为表面受阻路易斯对的形成提供了必要的氧化还原活性路易斯酸（Mn（IV）/Mn（III））和路易斯碱（O（-II）和OH（-I））位点。在所有催化剂中，LaMn _0.9 Cu _0.1 O ₃具有最高的光催化活性，实现了1.1 mmol g ^–1 h ^–1的乙烯产率和4.9%的乙烷转化率。

为了阐明反应途径以及表面受阻路易斯对在促进C-H活化中的作用，研究人员利用原位漫反射红外傅里叶变换光谱、固态魔角旋转技术探讨了乙烷吸附行为和Mn-H键形成质子核磁共振和密度泛函理论建模。在第一个 C-H 活化阶段，乙烷中的氢与路易斯碱氧或氢氧化物位点结合，形成 Mn-OH 或 Mn-OH ₂ （如图）。同时，在路易斯酸位点形成 Mn-C ₂ H ₅ 。在第二步中，锚定乙基的β-氢被Mn位点进一步激活，生成Mn-H物种，然后进行乙烯解吸和活性位点的再生。在光照下，假设光生电子和空穴分别位于路易斯酸和路易斯碱位点。这种定位增强了反应物和活性位点之间的相互作用，从而最大限度地减少了活化势垒。此外，与其他光热过程一样，照射引起的局部热量进一步加速了反应。这项研究令人信服地证明了表面受阻路易斯对工程策略在开发用于激活稳定分子的高效光催化剂方面的适用性。