Photocatalytic aerobic oxidation of alcohols for the direct synthesis of esters has received significant attention in recent years, but the relatively low efficiency and selectivity under visible light irradiation is the main challenge for their practical applications. Here, surface acidic sites were imparted onto metal-free heterogeneous photocatalysts by the protonation of carbon nitride (HMCN) to promote the activity for the esterification reaction through further adsorption and activation of the intermediate aldehyde. The activation of the substrate could be remarkably modulated through tuning the acidic sites on the surface of the photocatalyst, leading to a controllable reactivity of the catalytic reaction. The one-pot process for the direct aerobic oxidative esterification of alcohol exhibits high efficiency and selectivity under mild and additive-free conditions and the apparent quantum yield (AQY) of the photocatalytic esterification reaction is 0.41% at 420 nm. Moreover, a scalable photocatalytic process by the merging of a continuous flow system with the heterogeneous HMCN photocatalyst is demonstrated, combining high catalytic efficiency and stability at ambient temperatures and being promising for larger-scale applications.

醇的光催化有氧氧化用于酯的直接合成近年来受到了广泛的关注，但是可见光照射下相对较低的效率和选择性是其实际应用的主要挑战。在这里，表面酸性位通过氮化碳（HMCN）的质子化作用赋予无金属的多相光催化剂，以通过进一步吸附和活化中间醛来促进酯化反应的活性。底物的活化可以通过调节光催化剂表面上的酸性位点来显着地调节，从而导致催化反应的可控反应性。醇的直接好氧氧化酯化的一锅法在温和且无添加剂的条件下显示出高效率和选择性，并且光催化酯化反应的表观量子产率（AQY）在420 nm下为0.41％。此外，通过将连续流系统与非均相HMCN光催化剂合并，证明了可扩展的光催化工艺，该工艺结合了高催化效率和在环境温度下的稳定性，并有望用于大规模应用。