Shanghai Silicate Institute has made a series of progress in piezoelectric catalysis research

Related research background? Piezoelectric materials have a non-centrosymmetric structure, which can induce an asymmetric distribution of surface charges under the action of external mechanical force
.
The non-equilibrium charges accumulated on the surface can trigger electrochemical reactions, which can realize the activation of water and oxygen molecules and the production of active oxygen species under mild conditions, which can realize the conversion of small energy molecules (O2, H2O, CH4, etc.
), which is considered It is an important potential reaction pathway to realize green chemical synthesis
.
? Related research progress? Recently, the Energy and Environmental Catalytic Materials Research Group of Shanghai Institute of Ceramics, Chinese Academy of Sciences has prepared a series of semiconductor materials with piezoelectric catalytic effect through reasonable catalytic reaction system design, and carried out piezoelectric catalytic hydrogen evolution, The research work on the generation of hydrogen peroxide by piezoelectric catalysis and the conversion of methane by piezoelectric catalysis has revealed the activation mechanism and conversion reaction mechanism of small energy molecules on the catalyst surface.
This research work is useful for promoting the use of natural and artificial vibration energy to convert small energetic molecules.
It is of great significance for green energy
.
? Under the action of external ultrasound, a piezoelectric field can be generated inside the ultra-thin MoS2
.
As the ultrasonic energy increases, the built-in electric field generated inside the material increases, and the carrier separation efficiency increases.
Therefore, when the ultrasonic energy increases, the hydrogen production efficiency of MoS2 is greatly improved
.
Modification of MoS2 with electrical polarity and surface polarization not only increases the active sites on the surface of the material, but also accumulates the electrons separated by the built-in electric field and H+ at the same site, which further promotes the improvement of hydrogen production efficiency and can also build holes The capture site promotes the separation of carriers and achieves a high hydrogen production efficiency of about 1250 μmol·g-1·h-1
.
This idea of ​​coupling piezoelectric effect and catalysis provides new solutions for semiconductor catalysis and nano-energy conversion devices, and is expected to broaden the application of piezoelectric materials in the field of catalysis
.
The research results were published in Journal of Materials Chemistry A 6 (2018) 11909-11915
.
? Use piezoelectric force microscopy to characterize the piezoelectric response of BiOCl, C3N4 and other materials, and verify the piezoelectric catalytic active sites of these materials through the oxidation-reduction reaction of related metal ions
.
Under air atmosphere, ultrasonic BiOCl or C3N4 pure water suspension can obtain H2O2 yields of 28μmol/h and 34μmol/h, respectively, which are higher than the H2O2 yields obtained by the corresponding photocatalytic process, indicating that these materials have a positive effect on the piezoelectric field.
Oxygen molecules have a stronger catalytic effect, and the efficiency of piezoelectric catalytic reactions has the potential for further application development
.
The research results were published in ChemSusChem 11 (2018) 527-531, Journal of Materials Chemistry A 6 (2018) 8366-8373
.
? Utilizing the piezoelectric catalytic effect of calcium hydroxyphosphate HAp, the conversion of methane to lower alcohol is realized through the serial process of methane oxidation and methanol coupling
.
Through the adsorption of probe molecules and the Au3+ reduction reaction, it is verified that the mechanism of HAp under ultrasonic oscillation is piezoelectric catalysis rather than ultrasonic catalysis
.
Under ultrasonic oscillation, the induced charges on the surface of HAp can be used as surface cathode/anode to initiate electrochemical reactions to activate methane, oxygen and water molecules.
The hydroxyl radicals generated after the activation of oxygen and water molecules can attack the CH bond of methane.
Convert it into lower alcohol
.
Piezoelectric catalytic conversion of methane on HAp can obtain methanol, ethanol, and isopropanol products, with yields of 84.
4, 43.
2, and 9.
6 μmol g-1 h-1, respectively, without the production of carbon monoxide or carbon dioxide
.
This work extended the reaction path of methane conversion through carbon-carbon coupling and alleviated the excessive oxidation of methanol.
At the same time, it proposed an upgrade idea of ​​C1 compound based on piezoelectric catalysis
.
The research results were published in Nano Energy, 79(2021) 105449-105459.
? (A) Schematic diagram of piezoelectric catalytic conversion of methane on HAp? (b) The effect of ultrasonic oscillation power on conversion efficiency? "? (C) HAp hysteresis Loop and field-induced displacement curve? This research is supported by the National Natural Science Foundation of China and other projects
.