Unraveling how reactive facets promote photocatalysis at the molecular level remains a grand challenge, while identification of the reactive facets can provide guidelines for designing highly efficient photocatalysts and unravelling the microscopic mechanisms behind them. Recently, a series of polytriazine imides (PTIs) was reported with highly crystalline structures; all had a relatively low photocatalytic activity for overall water splitting. Here, high-angle annular dark-field scanning transmission electron microscopy, energy dispersive spectroscopy mapping, and aberration-corrected integrated differential phase contrast imaging were used to study PTI/Li⁺Cl⁻ single crystals before and after in situ photodeposition of co-catalysts, showing that the prismatic {10\(\bar 1\)0} planes are more photocatalytically reactive than the basal {0001} planes. Theoretical calculations confirmed that the electrons are energetically favourable to transfer toward the {10\(\bar 1\)0} planes. Upon this discovery, PTI/Li⁺Cl⁻ crystals with different aspect ratios were prepared, and the overall water splitting performance followed a linear correlation with the relative surface areas of the {10\(\bar 1\)0} and {0001} planes. Our controlling of the reactive facets directly instructs the development of highly efficient polymer photocatalysts for overall water splitting.

阐明反应性小平面如何在分子水平上促进光催化仍然是一个巨大的挑战，而识别反应性小平面可以为设计高效光催化剂和揭示其背后的微观机理提供指导。最近，报道了一系列具有高度结晶结构的聚三嗪酰亚胺（PTI）。都对整体水分解具有较低的光催化活性。在这里，高角环形暗场扫描透射电子显微镜，能量色散谱映射，和像差校正集成微分相位对比成像被用来研究PTI /锂⁺氯^-之前和之后的单晶中的助催化剂的原位光化学淀积，表明棱形{10\（\ bar 1 \） 0}平面比基础{0001}平面更具光催化活性。理论计算证实，电子在能量上有利于向{10 \（\ bar 1 \） 0}平面传输。已在此发现，PTI /锂⁺氯^-具有不同纵横比的晶体制备，并且整体水分解性能，随后用的相对表面面积的线性相关性{10 \（\杆1 \） 0}和{0001}飞机。我们对反应性面的控制直接指导着用于整体水分解的高效聚合物光催化剂的开发。