X-ray-Powered Micromotors

Abstract

Light-powered wireless manipulation of small objects in fluids has been of interest for biomedical and environmental applications. Although many techniques employing UV−vis−NIR light sources have been devised, new methods that hold greater penetrating power deep into medium are still in demand. Here, we develop a method to exploit X-rays to propel half-metal-coated Janus microparticles in aqueous solution. The Janus particles are simultaneously propelled and visualized in real-time by using a full-field transmission X-ray microscope. Our real-time observation discovers that the propulsive motion follows the bubble growth enhanced by water radiolysis near the particle surface under X-ray irradiation. We also show that the propulsion speed is remotely controlled by varying the radiation dose. We expect this work to open opportunities to employ light-powered micro/ nanomotors in opaque environments, potentially by combining with medical imaging or nondestructive testing.

Oxygen‐Deficient NiFe2O4 Spinel Nanoparticles as an Enhanced Electrocatalyst for the Oxygen Evolution Reaction

“…The charge-transfer resistances for different samples were determined by electrochemical impedance spectroscopy (EIS) in the frequency range between 100 mHz and 100 kHz at 1.65 V vs. RHE. The capacitance (C dl ) was estimated by CV, and no apparent Faradaic processes occurred in the region from 0.9 to 1 V vs. RHE with different scan rates (10,20,30,40,50,60,70,80,90, and 100 mV s À 1 ). The turnover frequency (TOF) was calculated according to equation TOF ¼ jA 4Fm (1) where j is the current density obtained at an overpotential of 400 mV in A cm À 2 , A is the surface area of the electrode, F is the Faraday Constant (96485 C mol À 1 ), and m is the number of moles of the active material.…”

“…However, the high cost and low abundance of these noble metals limit their potential, particularly for large-scale applications. [7][8][9][10] To lower catalyst cost, various transition metal-based oxide materials and their mixed structures have been intensively investigated as electrocatalysts for OER. [11][12][13][14][15][16] Mixed-metal spinel-type oxides, in the form of AB 2 O 4 , where A is a divalent metal ion and B is a trivalent metal ion, have been investigated as attractive potential candidates for use as OER catalysts due to their low cost, high stability, excellent redox properties, and high electrocatalytic activity.…”

Boosting the Sodiation Capability and Stability of FeP by In Situ Anchoring on the Graphene Conductive Framework

“…The morphologies of the FeP@rGO were investigated by field emission scanning electron microscopy (FESEM) in Fig Figure S3) through the similar synthesis route but without adding GO, which indicates that the large-surface area GO nanosheets can be a carrier to effectively suppress the aggregation of the FeP nanoparticles during synthesis process. [38,39] The detailed morphologies of the FeP@rGO sample were further investigated by transmission electron microscopy (TEM). From the image shown in Figure 3c, it is obvious that FeP nanoparticles with a maximum size less than 100 nm are anchored on porous graphene networks with plenty of void space around the nanoparticles which is expected to help buffer the volume expansion for the material during sodiation process.…”

Recent Advances in Effective Reduction of Graphene Oxide for Highly Improved Performance Toward Electrochemical Energy Storage

“…[74] The thermal-reduced graphene-based materials were widely researched and applied to obtain low-defect graphene for energy storage devices. This led to excellent improvement in electrochemical performance of such devices as Li-ion batteries (LIBs), [55,[75][76][77][78][79][80][81][82][83][84] Li-air batteries, [85][86][87][88] Li-sulfur batteries (LSBs), [89] Na-ion batteries (SIBs), [81,90] Al-ion batteries (AlBs), [47][48][49][50] and SCs. [91] Zhang et al [83] used graphite oxide (GO) and triphenylphosphine (TPP) as carbon and phosphorus sources for synthesizing phosphorus-doped graphene (PG) by thermal annealing reduction (e.g., 1000°C).…”