表面稳定单质铜的介孔二氧化钛的光催化产氢性能

采用十二烷基硫醇作为保护剂有效地稳定住了光催化过程中介孔二氧化钛(m-TiO₂)表面原位生成的Cu⁰物种。通过X射线衍射,X射线光电子能谱,高分辨透射电镜,高角环形暗场扫描透射电镜等手段对催化剂的组成结构进行了表征,发现催化剂中仅有Cu⁰物种存在。在紫外光照射下,以甲醛水溶液为牺牲试剂测试了Cu⁰物种对介孔二氧化钛产氢性能的影响,发现适量的Cu⁰纳米颗粒能够极大地提高介孔二氧化钛的产氢性能。当Cu⁰的物质的量分数为1.0%时,Cu⁰/m-TiO₂表现出最高的产氢速率,为725μmol·h^-1·g^-1。该样品中Cu⁰纳米颗粒的尺寸为(4.2±0.9)nm。此外,通过气相色谱检测到产生的H₂和CO₂的物质的量之比为2:1,表明部分氢气来自于水分解。     

基于后功能化工艺修饰类石墨相氮化碳及其光催化产氢性能研究（英文）

本研究设计了一种后功能化工艺方法修饰类石墨相氮化炭材料。通过此工艺成功得到了硼掺杂的介孔氮化炭材料,该材料比表面积高达125 m²/g,这为提升光催化分解水性能奠定了基础。利用X射线衍射、X射线光电子能谱,荧光光谱和紫外-可见光谱对材料进行了全面的表征。基于X射线光电子能谱分析,发现通过后功能化处理硼原子成功掺杂进入氮化炭的晶格中;通过吸收光谱分析得知,硼掺杂的介孔氮化炭材料增强了在可见光区的光吸收;通过荧光光谱分析得知,相比原始氮化炭材料,硼掺杂后的介孔氮化炭材料有着更低的荧光强度,意味着光生电子和空穴的分离得到了提升。对材料进行光催化分解水测试,后功能化处理得到的硼掺杂介孔氮化炭材料的产氢速率是原始氮化炭材料的10.2倍。此结论对后续利用后功能化工艺修饰材料提升材料性能具有一定的借鉴意义。     

杂原子HMS介孔分子筛的催化脱氢和加氢脱硫性能

ＭＣＭ４１［１］和ＨＭＳ［２］等介孔分子筛对大分子的扩散阻力较小且具有良好的热稳定性,特别是在合成中可以直接将各种杂原子引入骨架,从而调变其催化性能,因此目前介孔分子筛在催化中的应用引起了各国研究者的广泛兴趣．Ｔｉ,Ｚｒ,Ｖ,Ｃｒ,Ｍｎ,Ｃｕ和Ｆｅ...     

自旋电子学-光催化产氢交叉学科研究中的测试表征技术进展

清洁能源的研究和开发为解决化石燃料的日益枯竭问题带来了希望.氢能燃烧热值高,产物零污染,是理想的清洁能源.利用太阳能,通过光催化反应从水中制取氢气,是一条极有发展前景的制氢途径.然而,太阳能光催化制氢的发展受到许多因素的限制,特别是光电子传输过程中的电子-空穴复合及能量损失导致的电子输运效率低以及高的产氢产氧过电位导致水分解过程的势垒增大.自旋电子学的发展,为太阳能光催化制氢中的这些问题提供了解决之道.通过将自旋电子学的思路及原理应用于太阳能光催化制氢,借助自旋输运及电子隧穿可有效提高电子的输运效率,光电子的自旋极化还可降低产氢产氧过电位并抑制副产物的生成.测试表征技术的发展为揭示自旋电子学-太阳能光催化制氢交叉科学的内秉机理做出了重要贡献.然而,目前尚无相关文籍对此类测试表征技术的发展进行总结和评述.考虑到这些测试表征技术在自旋电子学-太阳能光催化制氢交叉科学研究中的重要作用,对它们进行归纳和总结,评述其发展面临的问题与挑战,探索并合理预测其未来的发展方向.     

LiNbO_3不同晶面的光催化产氢性能

研究了LiNbO3(001)、(100)和(110)晶面的光催化产氢性能。(001)、(100)和(110)3个晶面光催化产氢性能之比为7.8∶1.3∶1.0。LiNbO3[001]晶向存在电偶极矩和自发极化,有利于增加光生电子和空穴的分离效率,减少光生电子和空穴的复合,提高LiNbO3(001)面的光催化活性。LiNbO3(001)面的空穴有效质量最小,有利于光生空穴的迁移,从而减少光生电子和空穴的复合,也有利于光催化性能的提高。     

CdTiO_3纳米棒的可控制备及光催化产氢性能

以钛-乙二醇配合物纳米棒为模板,结合湿浸渍焙烧法制备了不同长度的钛酸镉(CdTiO3)纳米棒.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、广角X射线粉末衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)、热重分析仪(TG)及紫外-可见光谱仪(UV-Vis)等对前驱体及CdTiO3纳米棒进行了表征.结果表明,得到的CdTiO3纳米棒长度分别约为50,20和10μm,且无杂相,晶化度高,尺寸均一.负载1%(质量分数)铂作为助催化剂后,制备的不同长度CdTiO3纳米棒具有比CdTiO3纳米粒子更高的光催化产氢活性.其中,最长的CdTiO3纳米棒具有最高的产氢活性(~52.9μmol/h).     

含Ti的HMS介孔材料催化剂及其对丙烯环氧化催化性能的研究

分别用水热合成法和气相四氯化钛(TiCl4)接枝法制备了Ti-HMS和Ti/HMS催化剂.表征结果表明,经过气相TiCl4接枝后的样品依然保持HMS(Hexagonal Mesoporous Silica,缩写为HMS)介孔材料特征,钛(Ti)物种主要以四配位的活性位形式存在.经过甲基接枝处理的催化材料,增加了表面的疏水性.丙烯环氧化反应结果表明,SN-Ti/HMS具有更高的催化性能.在2 500 h的稳定试验中,过氧化氢异丙苯(CHP)转化率大于99.0%,环氧丙烷(PO)选择性大于96.0%.研究和优化了环氧化反应工艺条件.采用浓度为30%的CHP为原料,CHP重量空速为1.0 h-1,床层温度为100℃,反应压力为3.0 MPa.     

杂化介孔分子筛HMS的合成与表征

以十六胺(HDA)为模板剂,通过正硅酸乙酯和硅烷偶联剂一步法合成了杂化介孔分子筛HMS,并通过XRD、N2吸脱附、FT-IR、TG、SEM等手段对其进行结构表征.结果表明合成的材料具有良好有序的介孔结构、大的孔径(≈2.04.0 nm)和比表面积(>600 m2g-1),接近球形颗粒,尺寸在0.51μm之间.     

含氧空位缺陷钨酸铋光催化产氢性能研究

新型半导体光催化剂钨酸铋是目前研究广泛的光催化剂,但因其电子空穴对易复合的问题,限制了光催化产氢性能。为解决这一问题,采用锂-乙二胺溶液在钨酸铋表面构筑可控氧空位缺陷和金属缺陷。通过材料表征对比了钨酸铋经锂-乙二胺处理前后的变化,并对两者进行了产氢速率测试。钨酸铋在经过锂-乙二胺处理过后产生了氧空位缺陷和降价的金属中心,材料颜色从原先的黄白色转变为黄棕色,增强了光吸收能力。颗粒的主体结构以及物质成分并未发生变化,仍保持花球状颗粒结构,但处理后钨酸铋颗粒表面原先的光滑的片状结构变得粗糙,且方形纳米薄片锋利边缘变光滑,提高了光催化反应面积。这些变化使锂-乙二胺处理后的钨酸铋光催化产氢性能相比未处理之前得到了一定的提升。     

Photocatalytic Formic Acid Conversion on CdS Nanocrystals with Controllable Selectivity for H2 or CO

Formic acid is considered a promising energy carrier and hydrogen storage material for a carbon‐neutral economy. We present an inexpensive system for the selective room‐temperature photocatalytic conversion of formic acid into either hydrogen or carbon monoxide. Under visible‐light irradiation (λ>420 nm, 1 sun), suspensions of ligand‐capped cadmium sulfide nanocrystals in formic acid/sodium formate release up to 116±14 mmol H₂ g_cat^?1 h^?1 with >99 % selectivity when combined with a cobalt co‐catalyst; the quantum yield at λ=460 nm was 21.2±2.7 %. In the absence of capping ligands, suspensions of the same photocatalyst in aqueous sodium formate generate up to 102±13 mmol CO g_cat^?1 h^?1 with >95 % selectivity and 19.7±2.7 % quantum yield. H₂ and CO production was sustained for more than one week with turnover numbers greater than 6×10⁵ and 3×10⁶, respectively.     

AuPd和AgPd枝晶纳米催化剂催化甲酸分解制氢

由枝晶构成的AuPd和AgPd三维多孔泡沫薄膜在室温下分解甲酸制氢具有高催化活性。该高催化活性是由于纳米枝晶中存在大量的活性位点,如台阶、角、扭结、边缘以及合金间的电子效应。多孔泡沫膜除了具有较高的活性外,还具有其他优良的性能：在不需要有机添加剂的情况下,利用氢气泡模板法在Ti基板上可在5 min内快速沉积多孔泡沫催化剂,无需后处理便可用于催化甲酸分解制氢;通过将电沉积泡沫膜浸入或者拉出HCOOH+HCOONa溶液,可控制氢气的产生或停止;该泡沫催化剂通过去离子水清洗或者在H₂SO₄溶液中进行循环伏安扫描、干燥后就可活化重新使用。     

还原氧化石墨烯/介孔TiO2复合材料的合成及其光解水制氢性能

采用溶胶凝胶法,以钛酸四异丙酯(TTIP)为钛源,十六烷基三甲基溴化铵(CTAB)为模板剂合成了介孔二氧化钛样品mTiO_2,考察了合成温度、水量、模板剂用量和焙烧温度对其在紫外光条件下光催化产氢活性的影响。结果显示,在350℃下焙烧后,样品由无定形结构转变为锐钛矿相;随着焙烧温度的提高,锐钛矿相结构产物的结晶度提高,当焙烧温度超过550℃后,样品大部分转变为金红石相。以合成温度为30℃,模板剂用量(nCTAB/nTiO_2)为0.2,水量(nH2O/nTiO_2)为100,焙烧温度为450℃条件下合成的m-TiO_2样品为催化剂,当催化剂用量为0.4 g·L-1,体系中甲醇浓度高于20%(V/V)时,其紫外光条件下的光催化产氢活性达170 mmol·g-1·h-1。采用水热法将氧化石墨烯(GO)与m-TiO_2复合制备了一系列还原氧化石墨烯/介孔TiO_2复合材料(rGO/m-TiO_2),其晶相结构为锐钛矿相。当r GO复合量(wGO/wTiO_2)为0.01时,样品在紫外光下的产氢活性为241 mmol·g-1·h-1,能量转化效率达7.4%,较未复合样品提高了42.3%;在可见光条件下,其产氢活性达9 mmol·g-1·h-1。     

Recent Progress in Homogeneous Catalytic Dehydrogenation of Formic Acid

Recently, there has been a strong demand for technologies that use hydrogen as an energy carrier, instead of fossil fuels. Hence, new and effective hydrogen storage technologies are attracting increasing attention. Formic acid (FA) is considered an effective liquid chemical for hydrogen storage because it is easier to handle than solid or gaseous materials. This review presents recent advances in research into the development of homogeneous catalysts, primarily focusing on hydrogen generation by FA dehydrogenation. Notably, this review will aid in the development of useful catalysts, thereby accelerating the transition to a hydrogen-based society.     

Palladium Nanoparticles Supported on Titanium‐Doped Graphitic Carbon Nitride for Formic Acid Dehydrogenation

Pd nanoparticles (NPs) supported on Ti‐doped graphitic carbon nitride (g‐C₃N₄) were synthesized by a deposition–precipitation route and a subsequent reduction with NaBH₄. The features of the NPs were studied by XRD, TEM, FTIR, XPS, EXAFS and N₂‐physisorption measurements. It was found that the NPs had an average size of 2.9 nm and presented a high dispersion on the surface of Ti‐doped g‐C₃N₄. Compared to Pd loaded on pristine g‐C₃N₄, the Pd NPs supported on Ti‐doped g‐C₃N₄ exhibited a high catalytic activity in formic acid dehydrogenation in water at room temperature. The enhanced activity could be attributed to the small Pd NPs size, as well as the strong interaction between Pd NPs and Ti‐doped g‐C₃N₄.     

Pt/TiO2光催化分解甲酸制氢反应的原位红外光谱研究

用原位红外光谱研究了无氧条件下Pt/TiO2光催化甲酸制氢反应机理.结果表明,物理吸附的甲酸物种在光催化反应过程中向甲酸根离子转化,而甲酸根离子则逐渐向碳酸盐物种转化.水蒸气的添加显著促进了甲酸在Pt/TiO2上光催化反应的进行,并提高了产氢效率.提出了该光催化反应的可能机理.     

Synergic Catalysis of PdCu Alloy Nanoparticles within a Macroreticular Basic Resin for Hydrogen Production from Formic Acid

Highly dispersed PdCu alloy nanoparticles have been successfully prepared within a macroreticular basic resin bearing ?N(CH₃)₂ functional groups. This previously unappreciated combination of alloy is first proven to be responsible for the efficient production of high‐purity H₂ from formic acid (HCOOH) dehydrogenation for chemical hydrogen storage. By the addition of Cu, the electronically promoted Pd sites show significantly higher catalytic activity as well as a better tolerance towards CO poisoning as compared to their monometallic Pd counterparts. Experimental and DFT calculation studies revealed not only the synergic alloying effect but also cooperative action by the ?N(CH₃)₂ groups within the resin play crucial roles in achieving exceptional catalytic performances. In addition to the advantages such as, facile preparation method, free of additives, recyclable without leaching of active component, and suppression of unfavorable CO formation less than 3 ppm, the present catalytic system is cost‐effective because of the superior catalytic activity compared with that of well‐established precious PdAg or PdAu catalysts. The present catalytic system is particularly desirable for an ideal hydrogen vector in terms of potential industrial application for fuel cells.     

A Ruthenium‐Based Biomimetic Hydrogen Cluster for Efficient Photocatalytic Hydrogen Generation from Formic Acid

A ruthenium‐based biomimetic hydrogen cluster, [Ru₂(CO)₆(μ‐SCH₂CH₂CH₂S)] ( 1 ), has been synthesized and, in the presence of the P ligand tri(o‐tolyl)phosphine, demonstrated efficient photocatalytic hydrogen generation from formic acid decomposition. Turnover frequencies (TOFs) of 5500 h^?1 and turnover numbers (TONs) over 24 700 were obtained with less than 50 ppm of the catalyst, thus representing the highest TOFs for ruthenium complexes as well as the best efficiency for photocatalytic hydrogen production from formic acid. Moreover, 1 showed high stability with no significant degradation of the photocatalyst observed after prolonged photoirradiation at 90 °C.