Surface-enhanced Raman Spectroscopy (SERS) is a nondestructive technique for rapid detection of analytes even at the single-molecule level. However, highly sensitive and reliable SERS substrates are mostly fabricated with complex nanofabrication techniques, greatly restricting their practical applications. A convenient electrochemical method for transforming the surface of commercial gold wires/foils into silver-alloyed nanostructures is demonstrated in this report. Au substrates are treated with repetitive anodic and cathodic bias in an electrolyte of thiourea, in a one-pot one-step manner. X-rays absorption fine structure (XAFS) spectroscopy confirms that the AuAg alloy is induced at the surface. The unique AuAg alloyed surface nanostructures are particularly advantageous when served as SERS substrates, enabling a remarkably sensitive detection of Rhodamine B (a detection limit of 10⁻¹⁴ ​M, and uniform strong response throughout the substrates at 10⁻¹² ​M).

The construction of electrode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) has gradually been an appealing and attractive technology in energy storage research field. In the present work, a facile strategy of synthesizing ultrathin amorphous/nanocrystal dual-phase P-doped Bi₂MoO₆ (denoted as P-BiMO) nanosheets via a one-step wet-chemical synthesis approach is explored. Quite distinct from conventional two-dimensional (2D) nanosheets, our newly developed ultrathin P-BiMO nanosheets exhibit a unique tunable amorphous/nanocrystalline dual-phase structure with several compelling advantages including fast ion exchange ability and superb volume change buffer capability. The experimental results reveal that our prepared P-BiMO-6 electrode delivers an excellent reversible capacity of 509.6 mA·g⁻¹ after continuous 1,500 cycles at the current densities of 1,500 mA·g⁻¹ and improved rate performance for LIBs. In the meanwhile, the P-BiMO-6 electrode also shows a reversible capacity of 300.6 mA·g⁻¹ after 100 cycles at 50 mA·g⁻¹ when being used as the SIBs electrodes. This present work uncovers an effective dual-phase nanosheet structure to improve the performance of batteries, providing an attractive paradigm to develop superior electrode materials.

Mineral hydrogels have caught a lot of attention for their strong competency as artificial skin-like materials. Nonetheless, it remains a great difficulty in fulfilling in one hydrogel system a range of key functionalities that are needed for practical artificial skin applications, i.e., to be biocompatible, strain-sensitive, ion-conductive, elastic and robust, anti-swelling, and anti-freezing. Here we present a such type of versatile hydrogel that is not only capable to deliver all the above-mentioned key functionalities but also highly stable. This novel hydrogel is constructed by introducing a gelatinous and amorphous multi-ionic biomineral (denoted as Mg-ACCP, containing Mg²⁺, Ca²⁺, CO₃²⁻, and PO₄³⁻) into the network of biocompatible polyvinyl alcohol (PVA) and sodium alginate (SA). The presence of Mg²⁺ and PO₄³⁻ in this hydrogel helps prohibit the crystallization of the biominerals, leading to significantly improved stability. The hydrogel thus obtained delivers excellent mechanical performance due to the chelation between the mineral ions and the organic matrix, and high sensitivity even to subtle pressure and strain applied, such as slight finger bending and gentle tapping. Furthermore, the novel hydrogel features high ionic conductivity, high resistance to swelling, and extraordinary anti-freezing property, holding great promise for applications in different practical scenarios, particularly in aqueous or cold environments.

Fabrication of single-crystalline metal-organic framework (MOF) hollow nanostructures with two-dimensional (2D) morphologies is a challenging task. Herein, twin-like MOF nanobricks, a quasi-hollow 2D architecture, with multi-metal nodes and replaceable organic ligands, are uniformly and firmly grown on conductive Ni foam through a generic one-pot approach. The formation process of twin-like MOF nanobricks mainly includes selective epitaxial growth of Fe-rich MOF layer and simultaneously dissolution of the pre-formed Ni-rich metal-organic frameworks (MOFs), all of which can be ascribed to a special self-templated mechanism. The fantastic structural merits of twin-like MOF nanobrick arrays, featuring highly exposed active sites, remarkable electrical conductivity, and hierarchical porosities, enable this material for efficient electrocatalysis. Using bimetallic NiFe-MOFs grown on Ni foam as an example, the resultant twin-like nanobrick arrays can be directly utilized as three-dimensional (3D) integrated electrode for high-performance water oxidation in 1 M KOH with a low overpotential, fast reaction kinetics (28.5 mV·dec⁻¹), and superb stability. Interestingly, the unstable NiFe-MOFs were served as an oxygen evolution reaction (OER) pre-catalyst and the single-crystalline NiFe-MOF precursor can be in-situ topochemically regulated into porous and low-crystalline NiFeO_x nanosheets during the OER process. This work extends the hollowing strategy to fabricate hollow MOFs with 2D architectures and highlights their direct utilization for advanced electrocatalysis.

Metal foams have been intensively studied as three-dimensional (3-D) bulk mass-support for various applications because of their high conductivities and attractive mechanical properties. However, the relatively low surface area of conventional metal foams largely limits their performance in applications such as charge storage. Here, we present a convenient electrochemical method for addressing this problem using Cu foams as an example. High surface area Cu foams are fabricated in a one-pot one-step manner by repetitive electrodeposition and dealloying treatments. The obtained Cu foams exhibit greatly improved performance for different applications like surface enhanced Raman spectroscopy (SERS) substrates and 3-D bulk supercapacitor electrodes.

The capability of fast charge and fast discharge is highly desirable for the electrode materials used in supercapacitors and lithium ion batteries. In this article, we report a simple strategy to considerably improve the high rate capability of Co₃O₄ nanowire array electrodes by uniformly loading Ag nanoparticles onto the surfaces of the Co₃O₄ nanowires via the silver-mirror reaction. The highly electrically conductive silver nanoparticles function as a network for the facile transport of electrons between the current collectors (Ti substrates) and the Co₃O₄ active materials. High capacity as well as remarkable rate capability has been achieved through this simple approach. Such novel Co₃O₄–Ag composite nanowire array electrodes have great potential for practical applications in pseudo-type supercapacitors as well as in lithium ion batteries.