Boosting Photocatalytic Hydrogen Evolution Reaction by the Improved Mass Flow and Energy Flow Process Based on Ultrasound Waves

Abstract

Sun-driven photocatalytic hydrogen production reaction opens up possibilities for renewable energy systems. The reaction is the mass and energy conversion process between materials and the environment. Thus, the proper physical field introduction is the desired serious consideration to improve the mass flow and energy flow process. Here, we propose a piezo-enhanced photocatalytic system based on the ultrasound field to realize the adjustable built-in electric field favoring photo-induced carriers' transfer. As a proof of concept, the piezophotocatalyst is prepared through a hydrothermal method. On the basis of the photoelectric characterization and theory calculation, the dynamics of mass transfer is enhanced by the ultrasonic field's spatial compression and cavitation effect. Moreover, the surface redox reaction is accelerated because the chemical bond break−reformation process is improved under the support of the cavitation effect. Thus, an impressive hydrogen production rate of up to 13.09 mmol h −1 g −1 has been achieved with a ternary catalyst. A practical demonstration is also designed to actualize hydrogen production in the natural condition, proving the piezophotocatalytic system's practical advantages.

Bifunctional Multiferroic GdCrO3 Nanoassemblies for Sustainable H2 Production Using Electro- and Photocatalysis

“…In addition to rate, apparent quantum yield (AQY) is an important metric for comparing the effectiveness of the photocatalysts for H 2 generation. The AQY calculated was 23.2%, which is very high as compared to that for other systems such as the oxide BaZr 0.97 Ce 0.03 O 3 (6%) and Au@MoS 2 (21.3%), but a bit lower than quantum efficiency calculated for graphene oxide-Rh-SrTiO 3 aerogels (51.1%). − To study the charge transfer dynamics of the photocatalytic system, Mott–Schottky analysis was performed. GdCrO 3 depicted the negative flat band potential ( V fb ) and positive slope as shown in Figure b, which indicate that it acts as an n-type semiconductor, and the negative flat band potential indicates that hydrogen production is feasible.…”

Piezoelectric Polarization and Sulfur Vacancy Enhanced Photocatalytic Hydrogen Evolution Performance of Bi2S3/ZnSn(OH)6 Piezo-photocatalyst

“…The synergistic index of piezo-photocatalysis of different catalysts was evaluated according to the following equation: synergy index = H 2 evolution rate of piezo‐photocatalysis H 2 evolution rate of piezocatalysis + H 2 evolution rate of photocatalysis The piezo-photocatalytic synergistic indices of all samples were greater than 1. Among them, the highest synergistic index of 1.93 was found for 8% BS-12/ZSH, which indicated an efficient synergistic effect between light irradiation and ultrasound . Excessive BS-12 loading would reduce the specific surface area, so the H 2 evolution activity of 10% and 12% BS-12/ZSH was reduced.…”

“…Among them, the highest synergistic index of 1.93 was found for 8% BS-12/ZSH, which indicated an efficient synergistic effect between light irradiation and ultrasound. 45 Excessive BS-12 loading would reduce the specific surface area, so the H 2 evolution activity of 10% and 12% BS-12/ZSH was reduced. The piezo-photocatalytic H 2 performance of bare BS and BS with different sulfur vacancy concentrations is displayed in Figure S6a, indicating that the appropriate S-vacancy concentration was beneficial to the piezo-photocatalytic H 2 production.…”

Ultrasound‐Assisted Preparation and Performance Regulation of Electrocatalytic Materials

“…The speed of ultrasonic propagation in air at 20 °C is approximately 340 m s À 1 and reaches 1481 m s À 1 . [72][73][74] Ultrasonic waves can enhance chemical reaction rates and reduce reaction times. In a liquid medium, they propagate through the surrounding liquid, giving rise to a phenomenon known as the "cavitation effect," which involves the generation, development, and sudden collapse of minuscule bubble nuclei in the liquid.…”