Mingyong Cai

Large-Scale Tunable 3D Self-Supporting WO3 Micro-Nano Architectures as Direct Photoanodes for Efficient Photoelectrochemical Water Splitting

Hydrogen production from water based on photoelectrochemical (PEC) reactions is feasible to solve the urgent energy crisis. Herein, hierarchical 3D self-supporting WO3 micro-nano architectures in situ grown on W plates are successfully fabricated via ultrafast laser processing hybrid with thermal oxidation. Owing to the large surface area and efficient interface charge transfer, the W plate with hierarchical porous WO3 nanoparticle aggregates has been directly employed as the photoanode for excellent PEC performance, which exhibits a high photocurrent density of 1.2 mA cm-2 at 1.0 V vs Ag/AgCl (1.23 V vs RHE) under AM 1.5 G illumination and reveals excellent structural stability during long-term PEC water splitting reactions. The nanoscale and microscale features can be facilely tuned by controlling the laser processing parameters and the thermal oxidation conditions to achieve improved PEC activity. The presented hybrid method is simple, cost-effective, and controllable for large-scale fabrication, which should provide a new and general route that how the properties of conventional metal oxides can be improved via hierarchical 3D micro-nano configurations.

Durable and robust transparent superhydrophobic glass surfaces fabricated by a femtosecond laser with exceptional water repellency and thermostability

Superhydrophobic self-cleaning glass surfaces with good transparency and robustness have diverse applications such as in windshields for automobiles, windows, anti-fouling mirrors, safety glasses, and solar panels. Superhydrophobicity requires high surface roughness, which inevitably results in the loss of surface transmittance. To resolve this contradiction, herein, we report a novel approach using an ultrafast laser direct-writing-dispersed micro-pit array to provide basic roughness, guarantee sufficient unprocessed surface area for high transparency, introduce multiple-laser processing within each pit to induce maximized nano-structure roughness, and then to hydrophobize the surface with a layer of fluoroalkylsilane molecules to achieve good superhydrophobicity. Moreover, distributed periodic micropits with self-organized micro–nano rods, nano-ripples, and nanoparticles were fabricated on silica glass. The glass surfaces show superhydrophobicity with a static contact angle (SCA) of 161° with a 4 μL water droplet, a sliding angle (SA) lower than 2° with a 5 μL water droplet, and transparency over 92% in the visible and near-infrared light. By various robust durability tests, we confirmed that these transparent superhydrophobic glass surfaces exhibited persistent water repellency after being soaked in water for at least 168 h, strong impact resistance of water impinging beyond 9 kg for half-an-hour, and thermal stability up to 500 °C. We report a simple and efficient approach to achieve large-area transparent superhydrophobic self-cleaning glass surfaces with excellent robustness and durability that show great application potential in related areas.