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Developing efficient and durable non-precious metal-based catalysts for the oxygen evolution reaction (OER) in water electrolysis is crucial for large-scale and affordable hydrogen production. Many transition metal-based OER catalysts have been explored, but controlling their transformation into active oxyhydroxides during reconstruction, with fast reaction kinetics and low energy barriers, remains challenging. This article reports an ultrafast Joule heating strategy to synthesize efficient and stable amorphous transition metal phosphate electrocatalysts from metal chlorides and phytic acid precursors within 100 milliseconds at around 420 °C. The resulting amorphous CoFeNi phosphate coated on a superhydrophilic activated carbon cloth (CoFeNiPi@ACC) delivered a low overpotential of 235 mV at 10 mA cm−2, a small Tafel slope of 32.2 mV dec−1, and high stability for OER in 1.0 M KOH solution over 100 hours. The transient Joule heating process facilitates the rapid formation of an amorphous metal phosphate structure with abundant active sites, higher oxidation states for metal cations, self-reconstruction into active metal oxyhydroxides, and enhanced charge carrier diffusion rates, resulting in outstanding OER performance. This approach could be extended to other advanced material combinations for sustainable and efficient renewable energy production and storage. [ABSTRACT FROM AUTHOR]

Lightweight artificial muscles with large strain and large stress output have great application prospects in robotics, rehabilitation, prosthetic, and exoskeletons. Despite the excellent performance of carbon nanotube‐based artificial muscles in recent years, their widespread use is hindered by the high manufacturing costs associated with carbon nanotubes. In this paper, the study introduces a novel approach by developing artificial muscles based on pure conductive polymer coiled yarns. This achievement is facilitated by the successful fabrication of high‐strength conductive polymer microfibers. Furthermore, the study elucidates the molecular structural changes occurring during electrochemical processes that induce a substantial radial volume expansion in the microfibers. The resultant anisotropic volume change is magnified by the coiled yarn, yielding a remarkable contractile strain exceeding 11% at a high stress of 5 MPa, equivalent to lifting loads more than 4000 times their own masses, all achieved with a low input voltage of 1 V. Additionally, these conductive polymer‐based artificial muscles exhibit hydration‐induced contraction up to 33%, with swift recovery through electrical heating, leveraging their intrinsic high conductivity. This breakthrough positions high‐performance conductive polymer microfibers as a promising cost‐effective alternative to carbon nanotubes, establishing them at the forefront of lightweight artificial muscles. [ABSTRACT FROM AUTHOR]

Germanium-tin (GeSn) is a CMOS-compatible group-IV material. Its growth, however, is plagued by the tendency of Sn segregation and the generation of defects within the GeSn layer when it is grown on the lattice-mismatched substrate. Thus far, thin GeSn has been reported for use in a direct-band gap for near-mid infrared light source and photodetector. In this communication, we report the growth of high quality single-crystalline GeSn (~ 1 μm) with low compressive stress (-0.3%) and low defects (3 × 107 /cm2) on Ge buffer on Si substrate. The as-grown GeSn is then fabricated into pedestal waveguide of width 1.25 μm. An estimated propagation loss of 1.81 dB/cm and bending loss of 0.19 dB/ bend are measured at 3.74 μm. In the absence of Ge-O absorption peaks at 820 and 550 cm-1, under optimal fabrication and measurement condition, the proposed GeSn waveguide might possibly support light propagation for wavelength beyond 25 μm.

Smart hydrogels, renowned for their adaptability to environmental changes, have found widespread utility in the realms of bioelectronics and bio-machinery, encompassing applications such as drug delivery, tissue engineering, physiological sensing, and cellular regulation. Among these applications, electrically driven hydrogel actuators stand out due to their superior control, swift responsiveness, and seamless integration with electronic systems. They hold great potential in the development of multifunctional hydrogel-based machines, including soft robots and artificial muscles. Despite significant progress in the field of electrically driven hydrogels, including advancements in material design, operational principles, microfabrication techniques, and performance optimization across diverse applications, a comprehensive review dedicated to this topic remains notably absent. This review aims to provide an all-encompassing perspective on electrically driven hydrogel actuators, delving into their foundational principles, molecular and composite designs, fabrication methodologies, device configurations, and their applications in the realms of soft robotics and bio-machinery. Furthermore, it highlights the existing performance constraints, explores strategies for enhancement, and outlines potential future avenues for the utilization of electrically driven hydrogels. [ABSTRACT FROM AUTHOR]

Dialysis is an artificial process to remove excess urea toxins from the body through adsorption or conversion. Urea adsorption by emergent 2D materials such as MXenes is one probable approach. Based on density functional theory (DFT) studies, the surface of Ti3C2Tx (T = –O– and –OH) MXenes is not optimum for urea adsorption. Therefore, functionalization with 3d metal dopants (Cu, Co, and Ni) is proposed to improve their urea adsorption ability. DFT calculations indicate that oxygen-terminated Ti3C2O2 has a much better urea adsorption ability when doped with Cu, Co, and Ni, with adsorption energy (Eads) values of −2.11 eV, −1.90 eV and −1.72 eV, respectively. These adsorption energies are much more favourable than that of the undoped one (Eads = −0.52 eV). To verify the calculation results, MILD Ti3C2Tx, or MXenes synthesized via the safer and easier minimally intensive layer delamination (MILD) method, were utilized to simulate Ti3C2O2 since they have –O– termination as the dominant species. Experimentally, the adsorption studies found that low concentration of Cu, Co, and Ni on MILD Ti3C2Tx showed a urea removal efficiency of 21.9%, 6.0% and 0.2%, respectively, much better than 0% removal efficiency of unfunctionalized Ti3C2Tx. Therefore, both DFT calculations and experiments showed that various metal functionalized MXenes have a similar trend for urea adsorption, highlighting the feasibility of using the computational approach to predict urea adsorption and further opening a new promising direction for the urea adsorption. Finally, this study is also the first to examine synergistic effects of metal dopants and surface terminations on MXenes for urea adsorption. [ABSTRACT FROM AUTHOR]