Pt Single-Atoms on Structurally-Integrated 3D N-Doped Carbon Tubes Grid for Ampere-Level Current Density Hydrogen Evolution.

To date, the excellent mass-catalytic activities of Pt single-atoms catalysts (Pt-SACs) toward hydrogen evolution reaction (HER) are categorically confirmed; however, their high current density performance remains a challenge for practical applications. Here, a binder-free approach is exemplified to fabricate self-standing superhydrophilic-superaerphobic Pt-SACs cathodes by directly anchoring Pt-SAs via Pt-NxC4-x coordination bonds to the structurally-integrated 3D nitrogen-doped carbon tubes (N-CTs) array grid (denoted as Pt@N-CTs). The 3D Pt@N-CTs cathode with optimal Pt-SACs loading is capable of operating at a high current density of 1000 mA cm-2 with an ultralow overpotential of 157.9 mV with remarkable long-term stability over 11 days at 500 mA cm-2. The 3D super-wettable free-standing Pt@N-CTs possess interconnected vertical and lateral N-CTs with hierarchical-sized open channels, which facilitates the mass transfer. The binder-free immobilization adding to the large surface area and 3D-interconnected open channels endow Pt@N-CTs cathodes with high accessible active sites, electrical conductivity, and structural stability that maximize the utilization efficiency of Pt-SAs to achieve ampere-level current density HER at low overpotentials.

Structurally integrated 3D carbon tube grid-based high-performance filter capacitor.

Filter capacitors play a critical role in ensuring the quality and reliability of electrical and electronic equipment. Aluminum electrolytic capacitors are the most commonly used but are the largest filtering components, limiting device miniaturization. The high areal and volumetric capacitance of electric double-layer capacitors should make them ideal miniaturized filter capacitors, but they are hindered by their slow frequency responses. We report the development of interconnected and structurally integrated carbon tube grid-based electric double-layer capacitors with high areal capacitance and rapid frequency response. These capacitors exhibit excellent line filtering of 120-hertz voltage signal and volumetric advantages under low-voltage operations for digital circuits, portable electronics, and electrical appliances. These findings provide a sound technological basis for developing electric double-layer capacitors for miniaturizing filter and power devices.