宽光谱响应染料敏化半导体的构筑及其光催化产氢性能研究

发布时间：2018-04-29 00:40

  本文选题：染料敏化半导体 + 光催化产氢　； 参考：《武汉大学》2015年博士论文

【摘要】：构建高效、稳定及宽光谱响应的光催化产氢体系是当前新能源领域的挑战性课题。因染料的分子结构和吸光能力及范围可调、种类多样性等优点,染料敏化就成为提升宽隙半导体(如TiO2、g-C3N4等)的光谱响应范围及其光催化产氢性能的重要手段。但是传统的配合物、有机染料和天然色素等大多仅能吸收400-600nm的可见光,而不能充分利用太阳光的红光及红外区。为此,本文开展了染料的分子结构设计、共敏化以及可见/近红外宽光谱响应染料的探索,并深入探讨了其敏化半导体的光催化产氢性能及相关机理。主要研究内容和结论归纳如下：1.采用系列含/不含羧基的单/双核钌联吡啶类配合物敏化Ti02(P25)以提高可见光催化产氢能力。发现染料的分子结构及其与TiO2之间的结合方式对其敏化性能具有重大的影响：1)光照下的双核钌联吡啶类染料因其“天线-敏化中心”结构而具有的多途径分子内电荷转移过程(MLCT, MMCT等),有利于提高体系的光吸收效率；2)通过羧基与Ti02键合的染料在加速光生电子注入的同时,也利于光生电子的回传(复合)；而不含羧基的染料可通过O、N等与Ti02形成较弱的结合作用亦能形成光生电子的转移通道,但在Ti02表面建立的染料“基态吸附-氧化态脱附的动态平衡”可有效地抑制光生电子的回传(复合)。因此,不含羧基的双核钌联吡啶类染料敏化Ti02具有最好的产氢效率和稳定性,其在420nm单色光处的表观量子效率(AQY)为16.8%,是含羧基的单、双核钌联吡啶类染料的10倍左右。这对染料的分子设计、能带调控及其高效、稳定和宽可见光响应的敏化半导体产氢体系的构筑等具有重要的指导意义。2.将具有电子“推-拉”效应的非对称锌酞(萘)菁类配合物(Zn-tri-PcNc-1. Zn-tri-PcNc-2及Zn-tri-PcNc-3)敏化g-C3N4以提高其红光/近红外光响应能力。结果表明：1)酞菁配合物敏化g-C3N4的光谱响应范围可拓展到600-800nm的红光/近红外区；2)酞菁分子结构的非对称性、电子转移方向性、推拉电子基团等的共同作用是提升其敏化半导体的产氢性能的关键因素。由非对称锌酞(萘)菁敏化的g-C3N4在700 nm单色光处的AQY超过1.0%,远高于文献报道值(MgPc660 nm处～0.07%1MnPc:670 nm处～0.06%),有望推动太阳光中的红光／近红外光-氢能的转化效率的突破。3.将脱氧鹅胆酸(CDCA)共吸附剂引入到上述Zn-tri-PcNc-1-Pt/g-C3N4体系,发现CDCA起到抑制酞菁的聚集和提升敏化体系的光生电子转移效率的双重作用。经CDCA共吸附后,Zn-tri-PcNc-1-Pt/g-C3N4在λ≥500 nm光照下的产氢性能提升了50.5%,且在700 nm单色光处的A.QY提升到了1.85%,创造了酞菁类染料在敏化半导体产氢领域的新纪录。为进一步提升酞菁类染料对红光/近红外光的敏化产氢效率提供了新的思路。4.采用具有互补的光谱吸收能力的非对称酞菁类染料(Zn-tri-PcNc-1)及D-π-A有机染料(LI-4)成功构建了在400-800nm波段范围内具有光响应能力的新型光催化材料。发现共敏化材料(LI-4/g-C3N4/Zn-tri-PcNc-1)在λ≥420 nm光照下的产氢活性几乎为单一染料敏化体系(LI-4/g-C3N4和Zn-tri-PcNc-1/g-C3N4)活性的加和,且在420,500和700 nm单色光处的AQY分别高达16.3%,7.7%和1.75%。这为构建高效、稳定和宽光谱响应的产氢体系提供了一条新途径,有利于推动光-氢转换效能的突破和实际应用。5.基于廉价、无污染的抗坏血酸(AA)在Ti02表面原位形成的表面LMCT配合物及非对称酞菁类染料(Zn-tri-PcNc-1)构建了在400-800 nm波段具有较高产氢活性的共敏化材料(Zn-tri-PcNc-1-TiO2-AA)。研究发现：1)廉价、无污染的抗坏血酸可在TiO2表面原位、即时形成具有400-600 nm宽可见光响应能力的表面电荷转移配合物(AA-TiO2),其在λ≥420 nm光照下具有较好的产氢活性；2)共敏化材料Zn-tri-PcNc-1-TiO2-AA在λ≥420 nm光照下的产氢活性得到进一步提升,且在400-800 nm波段范围内均具有较高的AQY值,尤其是在420和700 nm单色光处的AQY分别为16.9%和0.97%。本研究打破传统DSSCs领域的共敏化模式,为进一步提升宽带隙半导体对可见光甚至近红外光的响应能力提供了全新的思路。6.将聚合物P3HT与g-C3N4复合构建了在400-700nm波段范围内具有光响应能力的P3HT/g-C3N4异质结光催化材料。研究发现：1)1牺牲试剂的种类及其参与的氧化半反应对该异质结材料的产氢性能具有重大的影响；2)以AA为牺牲试剂时,P3HT/g-C3N4在420和500nm单色光处的AQY分别高达77.4%和59.4%,且在700和760 nm单色光处的AQY亦分别高达3.2和1.7%,为聚合物类材料产氢领域的新记录。所构建的聚合物/聚合物异质结材料具有比一般染料更宽的可见/近红外光响应能力和更高的产氢活性,在提高可见/近红外宽光谱响应产氢效率和稳定性方面具有极大的发展潜力。
[Abstract]:The construction of photocatalytic hydrogen production system with high efficiency, stability and wide spectrum response is a challenging topic in the field of new energy. Because of its molecular structure, absorbability and range of absorbability and variety, the dye sensitization becomes the weight of the spectral response range of the wide gap semiconductor (such as TiO2, g-C3N4, etc.) and its photocatalytic hydrogen production performance. However, most of the traditional complexes, organic dyes and natural pigments can only absorb the visible light of 400-600nm, but can not make full use of the red and infrared light of the sun. Therefore, this paper has carried out the design of the molecular structure of the dye, the common sensitization and the exploration of the visible / near infrared broad spectrum response to the dye, and the sensitization half of the dye. The main research contents and conclusions are summarized as follows: 1. using a series of single / double nuclear ruthenium bipyridine complexes containing / without carboxyl group sensitized Ti02 (P25) to improve the capacity of hydrogen production in visible light. It is found that the molecular structure of the dye and the combination way with TiO2 are important for its sensitization. 1) 1) the multi-channel intramolecular charge transfer process (MLCT, MMCT, etc.) of the double nuclear ruthenium bipyridine dyes under the structure of the "antenna sensitization center" is beneficial to improving the optical absorption efficiency of the system. 2) the dye with the carboxyl and Ti02 bonds accelerates the photoelectron injection and is beneficial to the return of the photoelectron. The dye without carboxyl group can form a photoelectron transfer channel through weak binding between O, N and Ti02, but the dynamic equilibrium of the dye "base state adsorption oxidation state desorption" on the Ti02 surface can effectively inhibit the return of photoelectrons (compound). Therefore, the dyestuff of the non carboxyl biuclear ruthenium bipyridine The material sensitized Ti02 has the best hydrogen production efficiency and stability, and its apparent quantum efficiency (AQY) at 420nm monochromatic light is 16.8%, which is about 10 times of the monomer containing the carboxyl group and the double nuclear ruthenium bipyridine dye. It has important guiding significance for.2. to sensitize the asymmetric zinc phthalein (naphthalene) cyanine complexes (Zn-tri-PcNc-1. Zn-tri-PcNc-2 and Zn-tri-PcNc-3) with the electronic "push pull" effect to improve their red light / near infrared response ability. The results show that: 1) the spectral response range of the phthalocyanine complex sensitized g-C3N4 can be extended to the red light in 600-800nm. Near infrared region; 2) the non symmetry of the molecular structure of phthalocyanine, the direction of electron transfer and the interaction of the push and pull electronic groups are the key factors to improve the hydrogen production of the sensitized semiconductor. The AQY sensitized by asymmetric phthalide (naphthalocyanine) in the monochromatic light of 700 nm is over 1%, far higher than the reported value of the literature (MgPc660 nm to 0.07%1MnPc:6). 70 nm to 0.06%), it is expected to promote the transformation efficiency of the red / near infrared light and hydrogen energy in the solar light. The deoxy goose cholic acid (CDCA) Co adsorbent is introduced into the Zn-tri-PcNc-1-Pt/g-C3N4 system. It is found that CDCA plays a double role in inhibiting the aggregation of phthalocyanine and enhancing the photoelectron transfer efficiency of the sensitized system. By CDCA CO adsorption After that, the hydrogen production performance of Zn-tri-PcNc-1-Pt/g-C3N4 increased by 50.5% under the light of lambda 500 nm and increased to 1.85% at the 700 nm monochromatic light, creating a new record of the phthalocyanine dyes in the field of hydrogen production in sensitized semiconductors. It provides a new way of thinking for further upgrading the efficiency of the sensitized hydrogen production of the red / near infrared light by phthalocyanine dyes. Using asymmetric phthalocyanine dyes (Zn-tri-PcNc-1) and D- PI -A organic dyes (LI-4) with complementary spectral absorbability, a new photocatalytic material with light response ability in the range of 400-800nm band is successfully constructed. The hydrogen production activity of the co sensitized material (LI-4/g-C3N4/Zn-tri-PcNc-1) in the light of lambda 420 nm is almost single dye. The addition of the activity of the material sensitized system (LI-4/g-C3N4 and Zn-tri-PcNc-1/g-C3N4), and the AQY of 16.3%, 7.7% and 1.75%. at the 420500 and 700 nm monochromatic light respectively, provides a new way for the construction of hydrogen production system with high efficiency, stability and wide spectrum response. It is beneficial to promote the breakthrough of the efficiency of light hydrogen conversion and the actual application of.5. based on the cheap, and no The surface LMCT complexes and asymmetric phthalocyanine dyes (Zn-tri-PcNc-1) formed on the surface of the contaminated Ti02 (AA) have constructed a co sensitized material (Zn-tri-PcNc-1-TiO2-AA) with high hydrogen production activity in the 400-800 nm band. The study found that 1) is cheap, and the unstained ascorbic acid can be in situ on the TiO2 surface, with 40 in situ formation. 0-600 nm wide visible light response surface charge transfer complex (AA-TiO2) has better hydrogen production activity under the light of lambda > 420 nm; 2) the hydrogen production activity of the co sensitized material Zn-tri-PcNc-1-TiO2-AA under the light of lambda > 420 nm is further enhanced, and has a higher AQY value in the range of 400-800 nm wave segments, especially in 420. The AQY of 700 nm monochromatic light is 16.9% and 0.97%. respectively. This study breaks the common sensitization mode in the traditional DSSCs field, which provides a new idea to further enhance the response ability of broadband gap semiconductors to visible and near infrared light..6. combines the polymer P3HT with g-C3N4 to build the photoresponse within the 400-700nm band range. P3HT/g-C3N4 heterojunction photocatalytic materials. The study found: 1) the types of the 1 sacrificial reagents and their participation in the oxidation semi reaction have a significant effect on the hydrogen production of the heterojunction material; 2) when AA is sacrificed, the AQY of P3HT/g-C3N4 at 420 and 500nm monochromatic light is as high as 77.4% and 59.4% respectively, and AQY in the monochromatic light of 700 and 760 nm, respectively. It is also up to 3.2 and 1.7% respectively. It is a new record in the field of hydrogen production in polymer materials. The polymer / polymer heterojunction material has a wider visible / near infrared response ability and higher hydrogen production activity than the general dye. It has a great potential for improving the efficiency and stability of hydrogen production in the visible / near infrared wide spectrum response. Power.

【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ116.2
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本文编号：1817639