Abstract The interaction between a gas molecule and photocatalyst is vital to trigger photocatalytic reaction. The surface state of photocatalyst affects much in this interaction. Herein, adsorption of H2O molecules on s-triazine-based g-C3N4 was thoroughly studied by first-principle calculation. Although various initial adsorption models with multifarious locations of H2O molecules were built, the optimized models with strong adsorption energy pointed to the same adsorption configuration, in which the H2O molecule hold an upright orientation above the corrugated g-C3N4 monolayer. An intermolecular O–H…N hydrogen bond formed via the binding of a polar O–H bond in H2O molecule and a two-coordinated electron-rich nitrogen atom in g-C3N4. Under the bridging effect of this intermolecular hydrogen bond, electrons would transfer from g-C3N4 to the H2O molecule, thereby lowering the Fermi level and enlarging work function of g-C3N4. Interestingly, regardless of the substitute, i.e. g-C3N4 multilayer, large supercell and nanotube, this adsorption system was highly reproducible, as its geometry structure and electronic property remained unchanged. In addition, the effect of nonmetal element doping on adsorption energy was explored. This work not only disclosed a highly preferential H2O adsorbed g-C3N4 architecture established by intermolecular hydrogen bond, but also contributed to the deep understanding and optimized design in water-splitting process on g-C3N4-based photocatalysts.

中文翻译：

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H2O分子在s-三嗪基g-C3N4上的吸附

摘要 气体分子与光催化剂之间的相互作用对于引发光催化反应至关重要。光催化剂的表面状态在这种相互作用中影响很大。在此，通过第一性原理计算深入研究了 H2O 分子在基于 s-三嗪的 g-C3N4 上的吸附。尽管建立了具有多种 H2O 分子位置的各种初始吸附模型，但具有强吸附能的优化模型指向相同的吸附构型，其中 H2O 分子在波纹 g-C3N4 单层上方保持垂直取向。通过 H2O 分子中的极性 O-H 键和 g-C3N4 中的双配位富电子氮原子结合形成分子间 O-H…N 氢键。在这种分子间氢键的架桥作用下，电子将从 g-C3N4 转移到 H2O 分子，从而降低费米能级并扩大 g-C3N4 的功函数。有趣的是，无论替代物如何，即 g-C3N4 多层、大型超级电池和纳米管，该吸附系统都具有高度的可重复性，因为其几何结构和电子特性保持不变。此外，还探讨了非金属元素掺杂对吸附能的影响。这项工作不仅揭示了通过分子间氢键建立的高度优先的 H2O 吸附 g-C3N4 结构，而且有助于深入理解基于 g-C3N4 的光催化剂的水分解过程的优化设计。大型超胞和纳米管，这种吸附系统具有高度可重复性，因为其几何结构和电子性质保持不变。此外，还探讨了非金属元素掺杂对吸附能的影响。这项工作不仅揭示了通过分子间氢键建立的高度优先的 H2O 吸附 g-C3N4 结构，而且有助于深入理解基于 g-C3N4 的光催化剂的水分解过程的优化设计。大型超胞和纳米管，这种吸附系统具有高度可重复性，因为其几何结构和电子性质保持不变。此外，还探讨了非金属元素掺杂对吸附能的影响。这项工作不仅揭示了通过分子间氢键建立的高度优先的 H2O 吸附 g-C3N4 结构，而且有助于深入理解基于 g-C3N4 的光催化剂的水分解过程的优化设计。