Sun Qijun, researcher of Beijing Institute of nano energy and system, Chinese Academy of Sciences and Wang Zhonglin's team

Lead piezoelectric photocatalysis is based on the mechanism of piezoelectric and photocatalysis By applying external stress, the charge centers of cations and anions are asymmetric, the internal electric field is generated, which drives the separation of photo generated carriers, and the mechanical energy in the external environment is converted into chemical energy Recently, the application of piezoelectric heterostructures has attracted wide attention Sun Qijun, researcher of Beijing Institute of nano energy and systems, Chinese Academy of Sciences, worked with Wang Zhonglin's research team and Guo Limin, associate professor of science, Beijing University of Posts and telecommunications, to prepare a new type of Au X / BaTiO 3 nanostructure based on the principle of piezoelectric electronics Using the piezoelectric effect of BaTiO 3, the researchers further enhanced the separation of photogenerated carriers induced by SPR and effectively improved the photocatalytic process In this work, piezoelectric effect is introduced into the isoionic photocatalysis, which enhances the photocatalysis of Au X / BaTiO 3 heterostructure, and provides a new choice for the photocatalysis system such as pollutant treatment Relevant research results were published in adv funct Mater (DOI: 10.1002/adfm.201808737) Representative achievements of sun Qijun research group (1) piezoelectric regulated semiconductor devices: regulated channel Fermi level (ACS Nano, 2019, 13, 582); regulated Schottky barrier (nano energy, 2018, 50, 598); piezoelectric write in nonvolatile memory (ACS Nano, 2016, 10, 11037); piezoelectric potential driven electronic skin (adv mater., 2015, 27, 3411) (2) Friction potential regulated semiconductor devices: friction potential regulated double gate transistor (adv mater., 2018, 30, 1705088); friction ion electronics transistor (adv mater., 2019, 31, 1806905); direct contact friction electronics electronic skin (ACS Nano, 2018, 12, 9381) (3) Electronic skin sensor: self driving multi-stage sensor array (ACS Nano, 2018, 12, 254); high sensitive humidity sensor array (adv mater., 2017, 29, 1702076) (4) Piezoelectric / triboelectric potential controlled micro nano devices: piezoelectric / triboelectric self charging intelligent color changing energy package: (adv energy mater., 2018, 8, 1800069); piezoelectric / triboelectric high stability nano generator (nano energy, 2018, 57, 440) (5) plasmon photocatalytic materials and devices: proposal of MoS 2 / TiO 2 non-metallic plasmon system and photodegradation of water (energy Environ SCI., 2017, 11, 106); photocatalytic glycerin oxidation of aucu alloy plasmon (J mater Chem A, 2018, 8, 22005) Frontier research achievements: a new type of Au X / BaTiO 3 nano heterostructure is used for photocatalytic system in perovskite Pb (Zr, Ti) O 3, BaTiO 3 and other classic piezoelectric materials Applying external stress can cause the charge center displacement of anion and anion, and make the internal of the material produce dipole moment, so as to establish the internal electric field Driven by this internal electric field, some free carriers flow through the external circuit, which can promote the separation of electron hole pairs However, the poor conductivity of most piezoelectric materials limits the carrier transport In some bifunctional material systems, such as wurtzite materials (ZnO, Gan, InGaN) coupled with piezoelectric and semiconductor properties, piezoelectric potential can effectively regulate the generation, transmission, recombination and separation of carriers at the p-n junction, which is the basic research in the emerging fields of piezoelectric and piezoelectric optoelectronics Piezoelectric devices triggered by mechanical stimulation have made great achievements in new transistors, logic devices, memory and electronic skin Researchers from Beijing Institute of nano energy and systems, Chinese Academy of sciences have done a series of pioneering work in introducing piezoelectric and piezoelectric optoelectronics into photocatalytic processes Liu Hong's team used the spontaneous polarization potential of BaTiO 3 nanocrystals in response to ultrasound as an alternative built-in electric field to continuously separate photo generated carriers to improve photocatalytic activity (nano lett., 2015, 15, 2372) According to the mismatched thermal expansion coefficient of the two materials, Qin Yong's research team designed a heterostructure to improve the charge separation and significantly improve the photocatalytic performance by introducing and adjusting the piezoelectric potential on the piezoelectric materials of ZnO single crystal nano chips through thermal stress (ACS Nano, 2016, 10, 2636) Li Linlin's research team introduced the piezoelectric photoelectric effect of nanorod arrays to kill bacteria using photocatalysis (nano energy, 2018, 46, 29) Therefore, the development of more effective heterogeneous piezoelectric catalysts to further improve the efficiency of photocatalysis has great room for development Recently, dispersed noble metal nanocrystals with local surface plasmon resonance (LSPR) have become a research hotspot in the field of photocatalysis The advantages of plasma exciton photocatalyst lie in its abundant reaction sites and wide light response range Due to its stability and unique optical properties in visible light, Au nanoparticles are typical catalysts for plasmon BaTiO 3 nanocrystalline material is a very cheap and effective piezoelectric material, which can directly achieve part of the catalytic performance under the stimulation of small mechanical energy Therefore, the author hopes to improve the catalytic activity of piezoelectric / solar photocatalytic degradation of organic dyes by modifying Au nanoparticles on BaTiO 3 nanopiezoelectrics and combining LSPR with piezoelectric photocatalysis by using the coupling of surface "hot" electrons and piezoelectric potential The piezoelectric heterostructure proposed by the authors provides a simple and low-cost method for the preparation of high-performance photocatalysts, which has great potential applications In this work, the Au X / BaTiO 3 nano heterostructure was prepared, and the plasma photocatalysis was enhanced by introducing piezoelectric effect The piezoelectric polarization of BaTiO 3 nanocrystals during ultrasonic treatment inhibited the recombination of photogenerated electron hole pairs from LSPR, which effectively improved the photocatalytic process by inducing the formation of more free radicals The Au X / BaTiO 3 heterostructure photocatalyst was synthesized by a simple deposition precipitation method (Fig 1) The effects of Au loading, micro morphology and optical properties of heterostructure on photocatalytic degradation of dyes were studied The synergistic effect of plasma photocatalysis (AuNPs) and piezoelectric effect (BaTiO 3) effectively promoted the photocatalytic activity of Au X / BaTiO 3 heterostructure Figure 1 (a) preparation process of Au X / BaTiO 3 heterostructure; (B-D) SEM image of Au X / BaTiO 3 heterostructure (x = 2, 4, 6); (E) TEM image of au 4 / BaTiO 3; (F-G) HRTEM image of au 4 / BaTiO 3 (source: adv.funct Mater.) SEM and TEM characterization results show that with the increase of Au 3 + concentration in the reactant, 4-8 nm Au nanoparticles are uniformly deposited on the surface of BaTiO 3 nano cube, and the size of Au nanoparticles decreases slightly with the increase of Au content, which may be due to the addition of HAuCl 4 · 3H 2O It has a high concentration and a large number of nucleation points The close contact of the two crystals can promote the transfer of excited electrons from Au nanoparticles to BaTiO 3 substrate Fig 2 (a) XPS spectra of Au 4f in Au X / BaTiO 3; (b) UV Vis absorption spectra of Au X / BaTiO 3 (x = 0, 2, 4, 6); (c) PL spectra of au 4 / BaTiO 3 and BaTiO 3 nanocubes; (d) photoelectric flow response of au 4 / BaTiO 3 under simulated sunlight and full spectrum irradiation, respectively (source: adv.funct Mater.) au 4 / BaTiO 3 nanostructures have excellent optical properties (Fig 2) The data of absorption spectrum, photoluminescence spectrum and photocurrent response show that after Au nanoparticles are modified on BaTiO 3 nano cube, the optical absorption cross section is significantly improved with the increase of Au content due to the SPR induced by AuNPs, and the composite ratio of photo generated electron hole pair in au 4 / BaTiO 3 heterostructure is low, and it has excellent electron separation and transfer performance Fig 3 (a) in the presence of Au X / BaTiO 3 (x = 0, 2, 4, 6), Mo degrades with the change of irradiation time; (b) photocatalysis under full spectrum light irradiation; (c) catalysis process under ultrasonic and light irradiation; (d) comparison of sonocatalysis, photocatalysis and Sonophotocatalytic degradation of Mo in the presence of Au X / BaTiO 3 for 75 minutes (source: adv.funct Mater.) au 4 / BaTiO 3 showed the best photocatalytic performance in 75 minutes under full spectrum irradiation and ultrasonic excitation The degradation rate of methyl orange (MO) was 97% Ultrasonic vibration effectively induced piezoelectric polarization (equivalent to built-in electric field) in BaTiO 3 nano cube The built-in electric field is helpful to enhance the separation and transmission of photogenerated electron hole pair at the interface of heterostructure, promote the generation of free radicals and further oxidize organic compounds Therefore, the synergistic effect of piezoelectric polarization in BaTiO 3 nano cube and SPR of Au nano particles improves the photocatalytic performance of Au X / BaTiO 3 Fig 4 (a) schematic diagram of simulated piezoelectric effect in BaTiO 3 (3D model); (b) local electric field enhanced by Au nanoparticles on BaTiO 3; (c) SERS intensity distribution of 4-mercaptobenzoic acid (4-MBA) on au 4 / BaTiO 3; (d) schematic diagram of piezoelectric enhanced photocatalysis mechanism (source: adv.funct Mater.) through theoretical simulation, surface enhanced Raman scattering (SERS) test and energy band diagram analysis, the author fully elaborated the working mechanism of piezoelectric effect enhanced Catalysis (Figure 4) The built-in piezoelectric field in piezoelectric BaTiO 3 nanocrystals is the key to promote charge carrier migration and inhibit photogenerated carrier recombination, which is conducive to the continuous process of photocatalysis In this work, the coupling of piezoelectric potential and plasma photocatalysis process is used to realize the plasma photocatalysis activity enhanced by high-efficiency piezoelectric effect, which shows that piezoelectric plasma photocatalysis is is a new and effective advanced wastewater treatment technology that can be used for environmental purification Review of previous reports: researcher sun Qijun and research team Wang Zhonglin, Beijing Institute of nano energy and systems, Chinese Academy of Sciences Today, science and technology elements are increasingly valued in economic life, China has ushered in the "node of science and technology explosion" Behind the progress of science and technology is the work of countless scientists In the field of chemistry, in the context of the pursuit of innovation driven, international cooperation has been strengthened, the influence of Returned Scholars in the field of R & D has become increasingly prominent, and many excellent research groups have emerged in China For this reason, CBG information adopts the 1 + X reporting mechanism CBG information, chembeangoapp, chembeango official microblog, CBG wechat subscription number and other platforms jointly launch the column of "people and scientific research", approach the domestic representative research group, pay attention to their research, listen to their stories, record their demeanor, and explore their scientific research spirit.