During the rapid development of human civilization, energy crisis and environmental problems are inevitable issues with serious depletion of natural resources.Photocatalysis converts solar energy into chemical energy in an environmentally friendly way, which is considered as an effective approach to address the energy crisis and environmental pollution issues. Photocatalysis is also considered to have a great potential to ease the energy and environmental problems. However, the poor separation of the photogenerated electrons and holes seriously restrains the photocatalytic efficiency.
To fulfill these goals, a high-efficient photocatalyst should have broad solar light absorption, and effective separation and low recombination rate of photon-generated electron hole pairs. To reduce the recombination rate of photogenerated carriers, creation of built-in electric field as a driving force for charge separation has been recognized to be an effective strategy. Therefore, piezo-photocatalysis, in which the piezoelectric materials are subjected to simultaneous light irradiation and mechanical stress, has become a research focus. Unfortunately, the piezo-photocatalysis triggered by ultrasound technique requires a large energy consumption (with power consumption in the range of 50-600 W).
To circumvent this problem, for the first time in the field, we introduce a novel high-μ ribbon FeBSi-ZnO magnetocelectric (ME) nanocomposite, which exhibits the magnetoelectric-photocatalytic (ME-PC) coupling effect with an enhanced electrochemical activity for water remediation (with a power consumption of only 0.5 W). Compared to the previously and widely reported ultrasonic piezoelectric-photocatalytic (UP-PC) technique, the proposed ME-PC coupling system shows almost 100-1200 times higher energy efficiency for performing the same photocatalytic process. The high energy-efficiency catalysis can be attributed to the effective charge energy shifting generated by ME-PC coupling system, which promotes the surface redox reaction via transferred electrons and holes and the reactive oxygen species of •O-2 and •OH. It is also found that the kinetic rate of organic pollutant degradation under ME-PC activity is approximately three times faster than that of a pure photocatalytic process. The degradation efficiency for Indigo Carmine (IC), Methyl Orange (MO) and Rhodamine B (RB) organic pollutants are 98% (less than 60 minutes), 97% and 92% within 120 minutes, respectively, as shown in Figure1. Also, ME-PC activity could conduct 99.9% reduction of E. coli bacteria within 30 minutes.
This work may be extended to other built-in-field assisted photocatalytic platforms and offers an alternative way for designing future high-performance and low-powered magnetoelectric photocatalysis for water remediation.
Figure1. illustration of the working principle of a ME-photocatalytic (MEPC) system and its application for organic pollutant degradation. a) Schematic illustration of the ME-potential enhanced photocatalytic process of ZnO nanorods grown on Metglas/Cr/Au film under the applied magnetic field Hac, b) Water disinfection experiment with the nanostructured ME system against DH 5α E. coli bacteria, and c) UV-Visible spectra of indigo Carmine, Methyl Orange and Rhodamine B solutions varying with time due to ME-photocatalytic degradations.
The original ME-PC system proposed by the research team can be effectively and sustainably used for environmental remediation through the multi-physical field synergy strategy, and it has the characteristics of energy saving and low cost, showing the prospect of industrial application. This has been published in Materials Today Chemistry under the title "A highly energy-efficient magnetoelectric-photocatalytic coupling for water remediation." The article DOI is: 10.1016/j.mtchem.2023.101439. The first author of this work is M. Javad PourhosseiniAsl, a postdoctoral fellow at the College of Engineering and School of Materials Science and Engineering, Peking University; Professor Shuxiang Dong and researcher fellow Kailiang Ren are the corresponding authors of the paper.
The link to this paper：https://doi.org/10.1016/j.mtchem.2023.101439