Near infrared-light responsive WS2 microengines with high-performance electro- and photo-catalytic activities
de la Asuncion-Nadal, Victor; Jurado-Sanchez, Beatriz; Vazquez, Luis; Escarpa, Alberto
Tungsten disulfide (WS2)-based micromotors with enhanced electrochemical and photo-catalytic activities are synthesized using a greatly simplified electrochemical deposition protocol at room temperature involving exclusively tungstic acid and sulfate as metal and sulfur sources without further building chemistry. The WS2-based micromotors exhibit dual electrochemical and photo-catalytic behavior in the inner and outer layers, respectively, due to the combination of the unique properties of the sp2 hybridized WS2 outer layer with highly reactive WS2-induced inner catalytic layers, accounting for this material's exclusive enhanced performances. A rough inner Pt–Ni layer allows tailoring the micromotor propulsion, with a speed increase of up to 1.6 times after external control of the micromotor with a magnetic field due to enhanced fuel accessibility. Such a coupling of the attractive capabilities of WS2 with enhanced micromotor movement holds considerable promise to address the growing energy crisis and environmental pollution concerns.
(A) Schematic of the NIR responsive WS2/Ni/Pt micromotors with electrochemical and photo “inner and outer” catalytic activities. Red arrow indicates the direction of oxygen bubble ejection by Pt decomposition whereas green arrow indicates micromotor direction after orientation with a magnet. (B) Cyclic voltammograms corresponding to the electrodeposition of WS2 micromotors. (C) Raman spectra; (D) EDX and (E) SEM characterization of the micromotors. (F) SEM images of control MoS2 micromotors. Scale bars, 1 μm.