本研究利用第一性原理密度泛函理论，考察了 $hg-C_{3}N_{4}$ 量子点在增强电化学水分解方面的催化性能。所考虑的量子点尺寸位于实验报道的范围内（2nm - 4nm）[Zhou et al. ACS Nano 9, 12480 (2015)]。在所考虑的 $hg-C_{3}N_{4}$ 结构中引入氮空位以模拟实际情形，因为合成的 $hg-C_{3}N_{4}$ 量子点中已报道存在氮缺陷和碳缺陷。首先计算了结构和振动性质，以确保氮缺陷 $hg-C_{3}N_{4}$ 量子点的稳定性，随后研究了其电子性质和析氢反应（HER）性质。计算得到的 HER 参数，即吸附能、吉布斯自由能和过电位表明，所考虑的具有氮空位的 $hg-C_{3}N_{4}$ 量子点可作为中等有效的 HER 电催化剂。我们还考虑了该量子点溶解于水和乙醇中的情况，发现对于溶解在醇中的量子点，过电位大幅降低至 16 mV，而水溶液中也观察到显著降低。因此，本研究表明，溶解在乙醇中的氮缺陷 $hg-C_{3}N_{4}$ 量子点是通过电化学水分解实现可持续制氢催化的优异候选材料。
英文摘要：
The present study investigates the catalytic performance of a $hg-C_{3}N_{4}$ quantum dot aimed at enhancing electrochemical water splitting, using the first-principles density functional theory. The size of the considered quantum dot lies within the range reported experimentally (2nm - 4nm) [Zhou et al. ACS Nano 9, 12480 (2015)]. The nitrogen vacancies are created in the considered $hg-C_{3}N_{4}$ structure to simulate the realistic scenario, as the presence of nitrogen and carbon defects are reported in the synthesized $hg-C_{3}N_{4}$ quantum dots. First, the structural and vibrational properties are computed to ensure the stability of the nitrogen deficient $hg-C_{3}N_{4}$ quantum dots, and subsequently, their electronic and hydrogen evolution reaction (HER) properties are investigated. The calculate HER parameters, i.e., adsorption energies, Gibbs free energies, and overpotentials demonstrate that the considered $hg-C_{3}N_{4}$ quantum dot with nitrogen vacancies can be used as a moderately effective electrocatalyst for HER performance. We also considered the quantum dot to be dissolved in water and ethanol, and find that the overpotential gets drastically reduced to 16 mV for the alcohol dissolved quantum dot, while some significant reduction is seen for the aqueous solution also. As a result, this study suggests that the nitrogen-deficient $hg-C_{3}N_{4}$ quantum dots dissolved in ethanol are excellent candidates for catalysis aimed at sustainable hydrogen production via electrochemical water splitting.
Hydrogen/nitrogen/oxygen defect complexes in silicon from computational searches
Point defect complexes in crystalline silicon composed of hydrogen, nitrogen, and oxygen atoms are studied within density-functional theory (DFT). Ab initio Random Structure Searching (AIRSS) is used to find low-energy defect structures. We find new lowest-energy structures for several defects: the triple-oxygen defect, {3O}, triple oxygen with a nitrogen atom, {N, 3O}, triple nitrogen with an oxygen atom, {3N,O}, double hydrogen and an oxygen atom, {2H,O}, double hydrogen and oxygen atoms, {2H,2O} and four hydrogen/nitrogen/oxygen complexes, {H,N,O}, {2H,N,O}, {H,2N,O} and {H,N,2O}. We find t…
Nitrogen-doped Nanoporous Carbon Membranes Functionalized with Co/CoP Janus-type nanocrystals as Hydrogen Evolution Electrode in Both Acid and Alkaline Environment
自负载型电催化剂的制备及其直接作为能量转换电极的应用是材料化学和能源领域的研究热点。在此，我们报告了一种合成策略，以制备独立的分层结构，氮掺杂的纳米多孔石墨碳膜功能化与Janus型Co/CoP纳米晶体（称为HNDCM-Co/CoP），这是成功地应用于作为一个高效的，无粘合剂的电极在析氢反应（HER）。HNDCM-Co/CoP具有石墨化程度高、微孔/介孔/大孔三维连通、氮掺杂均匀、Co/CoP纳米晶分散性好以及薄碳层对纳米晶的限制作用等结构优点，在酸性和碱性条件下均表现出优异的电催化活性和长期运行稳定性。作为实际使用的概念验证，在我们的实验室中制备尺寸为5.6cm X 4cm X 60 μ π ι的HNDCM-Co/CoP的宏观片。在太阳能电池的驱动下，在碱性条件下（pH 14）进行水的电还原，并以16 ml/min的速率产生H2，表明其作为现实生活中的能量转换系统的潜力。
N-doped graphitic carbon materials hybridized with transition metals (compounds) for hydrogen evolution reaction: Understanding the synergistic effect from atomistic level
Hydrogen Storage on Transition-Metal-Decorated Nitrogen-Modified Carbon Nanoribbons
University of New England（新英格兰大学）；Karpagam Academy of Higher Education（卡尔帕甘高等教育学院）；Bhabha Atomic Research Centre（巴哈原子研究中心）；Homi Bhabha National Institute（霍米·巴巴国立研究所）；University of Canberra（堪培拉大学）；The University of Queensland（昆士兰大学）
Engineering NV Centers via Hydrogen-Driven Defect Chemistry in CVD Diamonds for Quantum Applications: NVHx Dissociations into NV, Origin of 468nm Center, and Cause of Brown Coloration
