Advancing supercapacitor system performance hinges on the innovation of novel electrode materials seamlessly integrated within distinct architectures. Herein, we introduce a direct approach for crafting nanorod arrays featuring crystalline/amorphous CuO/MnO_2−x. This reconfigured heterostructure results in an elevated content of electrochemically active MnO₂. The nanorod arrays serve as efficient capacitive anodes and are easily prepared via low-potential electrochemical activation. The resulting structure spontaneously forms a p–n heterojunction, developing a built-in electric field that dramatically facilitates the charge transport process. The intrinsic electric field, in conjunction with the crystalline/amorphous architecture, enables a large capacitance of 1.0 F·cm⁻² at 1.0 mA·cm⁻², an ultrahigh rate capability of approximately 85.4% at 15 mA·cm⁻², and stable cycling performance with 92.4% retention after 10,000 cycles. Theoretical calculations reveal that the presence of heterojunctions allows for the optimization of the electronic structure of this composite, leading to improved conductivity and optimized OH⁻ adsorption energy. This work provides new insights into the rational design of heterogeneous nanostructures, which hold great potential in energy storage applications.

The advancement of next-generation energy technologies calls for rationally designed and fabricated electrode materials that have desirable structures and satisfactory performance. Three-dimensional (3D) self-supported amorphous nanomaterials have attracted great enthusiasm as the cornerstone for building high-performance nanodevices. In particular, tremendous efforts have been devoted to the design, fabrication, and evaluation of self-supported amorphous nanomaterials as electrodes for energy storage and conversion devices in the past decade. However, the electrochemical performance of devices assembled with 3D self-supported amorphous nanomaterials still remains to be dramatically promoted to satisfy the demands for more practical applications. In this review, we aim to outline the achievements made in recent years in the development of 3D self-supported amorphous nanomaterials for a broad range of energy storage and conversion processes. We firstly summarize different synthetic strategies employed to synthesize 3D nanomaterials and to tailor their composition, morphology, and structure. Then, the performance of these 3D self-supported amorphous nanomaterials in their corresponding energy-related reactions is highlighted. Finally, we draw out our comprehensive understanding towards both challenges and prospects of this promising field, where valuable guidance and inspiration will surely facilitate further development of 3D self-supported amorphous nanomaterials, thus enabling more highly efficient energy storage and conversion devices that play a key role in embracing a sustainable energy future.

The current bottleneck facing further developments in fuel cells is the lack of durable electrocatalysts with satisfactory activity. In this study, a simple and fast one-pot wet-chemical method is proposed to synthesize novel Au@Pt star-like bimetallic nanocrystals (Au@Pt SLNCs) with a low Pt/Au ratio of 1:4, which show great electrocatalytic properties and outstanding stability toward the electro-oxidation reactions commonly found in fuel cells. The star-like Au core (90 ± 20 nm) is partially coated with 5 nm Pt nanocluster shells, a morphology which creates a large amount of boundaries and edges, thus tuning the surface electronic structure as demonstrated by X-ray photoelectron spectroscopy and CO-stripping measurements. This promotes excellent electrocatalytic performance towards the formic acid oxidation reaction in acidic media and the ethanol oxidation reaction in alkaline media, compared to commercial Pt or Au@Pt triangular nanoprisms, in which the Au core is fully coated by a Pt shell. Au@Pt SLNCs have the highest current density within the dehydrogenation potential range, needing the least potential to achieve a certain current density as well as the highest long-term stability. Because of the small amount of Pt usage, very fast synthesis, excellent electrocatalytic activity and durability, the proposed Au@Pt SLNCs have a promising practical application in fuel cells.