Preparation And Property Of Graphene Three Dimensional Assembly With Conjugated Molecules As Pillar Support Unit

Recently, the study of has received more and more attention. It is found that graphene three-dimensional assembly has a superior performance in the fields of photocatalytic hydrogen production and degradation, nanoelectronics, energy storage and conversion and biosensors, and it is considered to be a functional material with broad application prospect.This is mainly due to the three-dimensional graphene material has good flexibility, porosity,high specific surface area, excellent mass transfer performance. Therefore, a large number of three-dimensional graphene assembly and functional materials are prepared and got the corresponding research.In the assembly technology of three-dimensional graphene assembly, there are two main combination ways: non-covalent and covalent bond. Among them, the non-covalent connection method is not strong and not conducive to the electron transfer between the graphene nanosheets. So the three-dimensional graphene assembly obtained through the covalent bonding by using conjugated molecules as intermediates may has excellent electron transport performance. On the other hand, it is well known that monovalent metal ions can not be used as a cross-linker between two layers of graphene sheets to assemble a graphene material having a three-dimensional network structure. And people often get graphene/monovalent metal nanoparticle composites. Sponge has a rich three dimensional macroporous structure, if we use it as a carrier combined with graphene may obtain some graphene three-dimensional assembly functional materials with excellent performance. Based on the above considerations, we have studied the preparation and performance of graphene three-dimensional assembly, the specific contents and achievements are as follows:1. The nanometer multi-stage structure of silver nanoparticles/graphene/sponge was constructed by using ordinary commercial sponge as carrier and three-dimensional frame and graphene with silver nanoparticles as assembly unit. Then, its morphology and optical properties were systematically characterized. The effects of pH, temperature, amount of catalyst and sodium borohydride on the catalytic activity of the reduction of p-nitrophenol to p-aminophenol were investigated. The results show that this nanostructure is a efficient catalyst with excellent performance for the reduction of p-nitrophenol. Under its catalytic action, 10-4 moldm-3 p-nitrophenol can be degraded by 99% within 4 minutes. Compared with the traditional silver nanoparticles, the catalytic activity increased by 5.8 times.2. The hydrothermal technique was used to prepare the three-dimensional graphene with 4, 4-bipyridine as the pillared unit by the reaction between 4, 4-bipyridine with graphene with chloromethyl as the assembly unit. Then its morphology and optical properties were systematically characterized. The photocatalytic activity of the material and the influence of pH, sacrificial agent concentration and stirring speed on the photocatalytic activity were investigated. The cycling stability was also investigated. The results show that the three-dimensional graphene functional material monolith has better hydrogen production performance than P25 under UV irradiation. The hydrogen production rate is up to 1.07 molg-1h-1. In addition, we also found that in the neutral range, the material has the best hydrogen activity. When the sacrificial agent volume fraction is 15%, the material has the best hydrogen production activity. And the hydrogenation activity increases with the stirring speed increasing, which may be due to the influence of the material transmission speed in the solution. These experimental results provide theoretical support for the application of three-dimensional graphene-based functional materials with similar structures in the field of photocatalytic hydrogen production.3. Preparing three-dimensional graphene assembly by using pyridyl porphyrin as bridging body on FTO substrate through the reaction between tetrapyridyl-porphyrine and graphene with chloromethyl as the assembly unit by layer-by-layer assembly method. Then the morphology and optical properties of three-dimensional graphene assembly were systematically characterized. Then, the photocatalytic activity of the electrode and the effect of pH, temperature and degree of photoreduction on the photoelectrocheimical behavior were investigated. We found that under the same conditions, the timing current of the electrode is much greater than that of ordinary mixed graphene and porphyrin electrode. In addition, we also found that the electrode has a more negative hydrogen evolution potential than the normally mixed graphene and porphyrin electrodes by comparing the linear sweep curves.And with increasing of the number of layers, the photocurrent intensity of the electrode is greater. These results suggest that tetrapyridyl porphyrins provides an efficient electron channel for electron transport between graphene nanosheets. The use of this electronic channel can be constructed with a high activity of the photoelectric chemical hydrogen catalyst. This also has some reference for design of efficient photocatalyst in the future.