Improving Glycerol Photoreforming Hydrogen Production Over Ag2O-TiO2 Catalysts by Enhanced Colloidal Dispersion Stability.

Zhi Yang,Qingbin Song,Jingtao Zhang,Ying Chen,Weilin Zhong,Songping Mo,Chao Wang,Riyang Shu

doi:10.3389/fchem.2020.00342

Abstract

Solar-driven photocatalytic reforming of biomass-derived resources for hydrogen production offers a sustainable route toward the generation of clean and renewable fuels. However, the dispersion stability of the catalyst particles in the aqueous phase hinders the efficiency of hydrogen production. In this work, a novel method of mixing Ag2O-TiO2 photocatalysts with different morphologies was implemented to promote colloidal dispersion stability, thereby improving hydrogen production performance. A series of Ag2O-TiO2 nanoparticles with different morphologies were synthesized, and their dispersion stabilities in aqueous phase were investigated individually. Two types of Ag2O-TiO2 particles with different morphologies under certain proportions were mixed and suspended in glycerol aqueous solution without adding any dispersant for enhancing dispersion stability while reacting. From the results, photocatalytic hydrogen production was found to be strongly correlated to colloidal dispersion stability. The mixed suspension of Ag2O-TiO2 nanosphere and nanoplate achieved an excellent colloidal dispersion stability without employing any additives or external energy input, and the photoreforming hydrogen production obtained from this binary component system was around 1.1–2.3 times higher than that of the single-component system. From the calculated hydrogen production rate constants between continuous stirring and the binary system, there was only <6% difference, suggesting an efficient mass transfer of the binary system for photoreforming hydrogen production. The proposed method could provide some inspiration to a more energy-efficient heterogeneous catalytic hydrogen production process.

Highlights

Photoreforming hydrogen production route has been attracting great attention due to its integration of both solar energy and renewable sources utilization (Liu et al, 2014; Yu et al, 2015; Sadanandam et al, 2017)
It is worth noting that a large number of biomass-derived substrates, such as bio-alcohols, could be used for this photoreforming hydrogen production process
The pore structures and Brunauer-Emmett-Teller measurements (BET) surface areas of the asprepared samples were detected by the N2 adsorption– desorption measurement

Summary

INTRODUCTION

Photoreforming hydrogen production route has been attracting great attention due to its integration of both solar energy and renewable sources utilization (Liu et al, 2014; Yu et al, 2015; Sadanandam et al, 2017). Physical dispersion such as ultrasonic dispersion and mechanical dispersion and chemical dispersion such as dispersant or surfactant addition and nanoparticle surface modification were pointed out to be effective for improving the stability of TiO2 particles in water (Kim and Nishimura, 2012; Othman et al, 2012) Those methods requiring extra external energy input (e.g., ultrasonic dispersion, mechanical stirring, or electromagnetic stirring, etc.) obviously break the energy balance and increase the cost of large-scale application of photocatalytic hydrogen production. The mixed suspension of TiO2 nanosphere and nanosheet still showed great colloidal dispersion stability and photocatalytic hydrogen production promoting at a specific mixing ratio. This study attempts to investigate the dispersion stability of Ag2O-TiO2-based photocatalysts with different morphologies and its effect on photocatalytic activity for photoreforming hydrogen production. The surface energy was calculated by the CASTEP module in Materials Studio (MS) on the basis of DFT

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT