【作者】 李敏；

【导师】 李松杰； 禹晓梅；

【作者基本信息】 郑州大学 ， 材料与化工（专业学位）， 2025， 硕士

【摘要】 随着经济的发展与生活方式的改善,能源短缺和环境污染成为当下急需解决的问题。氢能因其具有纯度高、无污染、稳定高效等优点引起了人们的广泛关注。光电化学(PEC)分解水制氢能够将太阳能直接转化为氢能,有效地缓解了能源短缺和环境污染等问题。然而,析氧反应(OER)的缓慢反应动力学限制了该技术的发展。类石墨相氮化碳(CN)是一种无毒、物理化学性质稳定的有机半导体,因其对可见光响应、价格低廉、制备工艺简单、结构易于调控等优势而被广泛应用于光电化学能源转化领域。由于其导电性差、比表面积小、光生载流子复合严重等问题,导致光电转化效率较低。本研究通过制备富氮CN光阳极增加其比表面积,提升了电荷的迁移速率;通过构建ZIF-67/N-CN异质结为光生电荷提供了新的迁移路径,抑制了光生电子与空穴的复合;通过添加有机导电聚合物聚吡咯(PPy)增强了导电性,提升了光生电子的迁移速率。主要的研究内容如下:(1)采用前驱体刮涂-气相沉积法在FTO表面原位生长CN薄膜,通过调控前驱体的组成、原料配比等工艺条件,获得与FTO紧密结合的CN光阳极。结果表明,在氮气保护下,以三聚氰胺-三聚氰酸超分子混合前驱体刮涂制备的薄膜经高温气相沉积,得到表面均匀、结构稳定的CN/FTO光阳极。在可见光照射下(400-1200nm)、1.0MKOH溶液中,于1.23Vvs.RHE处的光电流密度为35μA/cm2。在此基础上对前驱体组成进一步调控,获得的富氮氮化碳(N-CN/FTO)光阳极的光电流密度达到57 μA/cm2,其光电流的增强归因于电极比表面积的增加以及电荷迁移速率的提升。(2)为有效抑制光生电子与空穴的复合,采用溶剂法在N-CN/FTO表面原位生长ZIF-67纳米层以构筑ZIF-67/N-CN/FTO复合光阳极。探索了负载的ZIF-67的元素比例和反应时间对光电化学分解水析氧性能的影响。结果表明,当金属(Co(NO3)2·6H2O)与配体(2-甲基咪唑)的摩尔比为1:4,在ZIF-67生长90 min后放入N-CN/FTO薄膜,反应30 min获得ZIF-67/N-CN/FTO复合光阳极,该光阳极的光电流密度可达89 μA/cm2。本实验制备的ZIF-67/N-CN Ⅱ型异质结为光生电荷提供了新的迁移路径,加强了电子与空穴的分离,降低了电荷载流子的迁移阻力,有效提升了光电化学析氧性能。(3)为进一步增强ZIF-67/N-CN/FTO中光生电子的迁移速率,在ZIF-67制备过程中加入导电聚合物PPy,制备出PPy@ZIF-67/N-CN/FTO光阳极。结果表明,PPy在ZIF-67中的掺杂有效增强了光生电荷的迁移,抑制了光生电子与空穴的复合,提升了光电化学析氧性能。制备的最佳复合光阳极光电流密度高达140 μA/cm2,分别是N-CN/FTO和ZIF-67/N-CN/FTO光电流密度的2.46倍和1.57 倍。更多还原

【Abstract】 As the economy and lifestyle improve,energy shortages and environmental pollution have become urgent issues that need to be addressed.Hydrogen energy has garnered widespread attention due to its high purity,pollution-free nature,and stable efficiency.Photoelectrochemical(PEC)water splitting for hydrogen production can directly convert solar energy into hydrogen energy,effectively alleviating problems related to energy shortages and environmental pollution.However,the slow kinetics of the oxygen evolution reaction(OER)limit the development of this technology.Carbon nitride(CN),a class of graphitic-like material,is a non-toxic organic semiconductor with stable physicochemical properties.It is widely used in the field of photoelectrochemical energy conversion due to its visible light responsiveness,low cost,simple preparation process,and easy structural tunability.However,issues such as poor electrical conductivity,limitted specific surface area,and severe recombination of photogenerated carriers lead to low photoelectroconversion efficiency.This study aims to enhance the specific surface area of nitrogen-rich CN photoanodes to improve charge transfer rates;construct ZIF-67/N-CN heterojunctions to provide new pathways for photogenerated charge migration and suppress the recombination of photogenerated electrons and holes;and enhance conductivity by adding the organic conductive polymer polypyrrole(PPy)to increase the migration rate of photogenerated electrons.The main research content is as follows:(1)A precursor scraping-coating and vapor deposition method was employed to in situ grow CN films on the surface of FTO.By adjusting the composition of the precursor and the material ratio,a CN photoanode tightly bonded to the FTO substrate was achieved.The results indicate that,under nitrogen protection,the film prepared by scraping a supramolecular mixture of melamine and cyanuric acid as the precursor underwent high-temperature vapor deposition,resulting in a CN/FTO photoanode with a uniform surface and stable structure.Under visible light illumination(400-1200 nm)in a 1.0 M KOH solution,the photocurrent density at 1.23 V vs.RHE was measured to be 35 μA/cm2.Furthermore,by further optimizing the precursor composition,the resulting nitrogen-rich carbon nitride(N-CN/FTO)photoanode achieved a photocurrent density of 57 μA/cm2.Enhanced photocurrent stems from the electrode’s larger surface area and more efficient charge transport.(2)To effectively suppress the recombination of photogenerated electrons and holes,ZIF-67 nanosheets were in situ grown on the surface of N-CN/FTO using a solvent method to construct the ZIF-67/N-CN/FTO composite photoanode.The effects of the element ratio of the loaded ZIF-67 and the reaction time on the photoelectrochemical water-splitting performance for oxygen evolution were investigated.The results indicate that when the molar ratio of metal(Co(NO3)2·6H2O)to ligand(2-methylimidazole)is 1:4,and ZIF-67 is grown for 90 minutes before being placed on the N-CN/FTO film for an additional 30 minutes,the resulting ZIF-67/NCN/FTO composite photoanode achieves a photocurrent density of up to 89 μA/cm2.The ZIF-67/N-CN type II heterojunction prepared in this experiment provides new migration pathways for photogenerated charges,enhances the separation of electrons and holes,and reduces the migration resistance of charge carriers,effectively improving the photoelectrochemical performance for oxygen evolution.(3)To further enhance the migration rate of photogenerated electrons in ZIF-67/NCN/FTO,conductive polymer PPy was incorporated during the preparation of ZIF-67,resulting in the fabrication of the PPy@ZIF-67/N-CN/FTO photoanode.The results indicate that the doping of PPy in ZIF-67 effectively enhances the migration of photogenerated charges,suppresses the recombination of photogenerated electrons and holes,and improves the photoelectrochemical performance for oxygen evolution.The optimized composite photoanode achieved a photocurrent density of up to 140 μA/cm2,which is 2.46 times and 1.57 times greater than the photocurrent densities of NCN/FTO and ZIF-67/N-CN/FTO,respectively.更多还原