Molten Salt Self-Template Synthesis Strategy of Oxygen-Rich Porous Carbon Cathodes for Zinc Ion Hybrid Capacitors

Porous carbon materials are widely used in capacitive energy storage devices because of their chemical stability, low cost, and controllable textures. Molten salt self-template methods are powerful and sustainable synthesis strategies for preparing porous carbons with tunable pore textures and surface chemistries. Herein, we propose a self-template synthesis strategy for preparing oxygen-rich porous carbons (ORC) by directly carbonizing potassium chloroacetate (ClCH2COOK) as the single carbon source. The potassium chloride salts generated in the carbonization play the roles of the template and etchant agent in the pore formation process. The as-prepared ORC samples feature abundant mesopores (average pore sizes of 1.95–2.19 nm and mesopore ratio of 36.4%), high specific surface areas (1410–1886 m2 g–1), and high oxygen doping levels (4.3–8.2 atom %). The zinc ion hybrid capacitors with an ORC cathode exhibited an ultrahigh capacitance of 308 F g–1 at 0.5 A g–1 and a high energy density of 136.5 Wh kg–1 at a power density of 570 W kg–1. Density functional theory demonstrates that oxygen-containing functional groups are conducive to the adsorption of Zn ions. Our work proposes a general synthesis methodology for the synthesis of oxygen-rich porous carbons for a variety of electrochemical energy storage devices

Thermally Stable Cellulose Nanocrystals toward High-Performance 2D and 3D Nanostructures

Cellulose nanomaterials have attracted much attention in a broad range of fields such as flexible electronics, tissue engineering, and 3D printing for their excellent mechanical strength and intriguing optical properties. Economic, sustainable, and eco-friendly production of cellulose nanomaterials with high thermal stability, however, remains a tremendous challenge. Here versatile cellulose nanocrystals (DM-OA-CNCs) are prepared through fully recyclable oxalic acid (OA) hydrolysis along with disk-milling (DM) pretreatment of bleached kraft eucalyptus pulp. Compared with the commonly used cellulose nanocrystals from sulfuric acid hydrolysis, DM-OA-CNCs show several advantages including large aspect ratio, carboxylated surface, and excellent thermal stability along with high yield. We also successfully demonstrate the fabrication of high-performance films and 3D-printed patterns using DM-OA-CNCs. The high-performance films with high transparency, ultralow haze, and excellent thermal stability have the great potential for applications in flexible electronic devices. The 3D-printed patterns with porous structures can be potentially applied in the field of tissue engineering as scaffolds

Visualization 1: Coreless side-polished fiber: a novel fiber structure for multimode interference and highly sensitive refractive index sensors

Field evolution at 1292 nm in the cross-section of CSPF Originally published in Optics Express on 06 March 2017 (oe-25-5-5352

Visualization 2: Coreless side-polished fiber: a novel fiber structure for multimode interference and highly sensitive refractive index sensors

Field evolution at 1322nm in the cross-section of CSPF Originally published in Optics Express on 06 March 2017 (oe-25-5-5352

Sensing and Exploiting Static Femto-Newton Optical Forces by a Nanofiber with White-Light Interferometry

Optical force determines the fundamental process of momentum exchange between light and matter. However, owing to the weak mechanical effect of the optical force and relatively large stiffness of optomechanical devices, pico-Newton (10^–12 N) optical force is required to manipulate micro/nanoparticles and the optical response of optical devices. It is still extremely challenging to sense static femto-Newton (fN) optical forces and exploit such forces to actuate micro-optical devices. Here, using a tapered nanofiber (TNF) with a high mechanical efficiency of 2.13 nm/fN, a sensitive and cost-effective scheme is demonstrated to generate, sense, and exploit fN optical force. Strong light coupling from the TNF to a glass substrate can result in a fN repulsive optical force, which can induce a TNF deformation of up to 425.6 nm. Such a large deformation allows white-light interferometry to detect a fN static optical force (5.2 fN). Moreover, the high optomechanical efficiency (15.6 nm/μW) allows us to all-optically control the signal power at values ranging from 0.09 to 17.1 μW with only microwatt pump power, which paves the way toward microwatt and fN-optical-force optomechanical devices