Inducing piezoelectricity in distorted rutile TiO_(2)for enhanced tetracycline hydrochloride degradation through photopiezocatalysis

Various material design strategies have been developed to enhance photocatalytic performance of TiO_(2).However,no report is available on applications of the photopiezocatalysis strategy on TiO_(2)due to its lack of piezoelectricity.Here we developed a low-temperature molten salt etching process to create rutile TiO_(2)nanoparticles by etching[MgO_(6)]octahedrons away from MgTiO_(3)by molten NH_(4)Cl,during which a lattice distortion occurred in TiO_(2).The lattice distortion broke the structure symmetry of rutile TiO_(2)and subsequently endowed these rutile TiO_(2)nanoparticles with an unusual piezoelectric response with the maximum effective piezoelectric coefficient(d_(33))of~41.6 pm/V,which had not previously been found in TiO_(2)photocatalysts.Thus,the photopiezocatalysis strategy was applied for the first time to enhance the photocatalytic performance of these TiO_(2)nanoparticles.The creation of lattice distortion to induce piezoelectricity could be extended to other photocatalysts that the photopiezocatalysis strategy has not been applied to and may generate novel functionalities for various technical applications.

Highly efficient sono-piezo-photo synergistic catalysis in bismuth layered ferroelectrics via finely distinguishing sonochemical and electromechanochemical processes

Ultrasonic stimulation induced polarization behaviors in ferroelectric materials have been extensively explored in catalytic degradations.However,the ultrasonic wave similarly can realize dye degradation by the sonocatalysis behavior,which is always neglected in most reports on in-situ ultrasound-induced piezoelectric catalysis,so that people might overestimate piezocatalytic contributions.For this,we designed a series of visible light sensitive bismuth layered ferroelectric materials(BLFMs),M_(0.5)Bi_(2.5)Nb_(2)O_(9)(MBN,M=Li,Na,and K).It is found that the cavitation-induced degradation rates of Rhodamine B(RhB)strongly depend mechanical stirring speeds under a fixed ultrasonic power,which gradually increases with it,and reaches 77.9%(500 rpm and 3 h).Under lower stirring speed and reaction time(<50 rpm and 2 h),the cavitation effect is almost negligible,only piezocatalysis behavior occurs,which can be used as a key condition to distinguish the piezocatalysis and sonocatalysis.In particular,the degradation rate constant of Na_(0.5)Bi_(2.5)Nb_(2)O_(9) catalyst reaches up to 4.943×10^(-2) min^(-1) by the coupling of sonocatalysis,piezocatalysis and photocatalysis,which is much higher than that of single photocatalysis(0.491×10^(-2) min^(-1)),piezocatalytic(1.6×10^(-3) min^(-1)),and sonocatalysis(0.756×10^(-2) min^(-1)).These results may provide a feasible strategy of further improving catalytic degradation efficiency,and accurately determining the sonocatalysis and piezocatalysis contribution.