Yan Lu,Radian Popescu,Dagmar Gerthsen,Yichen Feng,Wei-Ren Su,Yu-Kuei Hsu,Ying-Chu Chen
Hydrogen (H2) fuel production from hazardous contaminants is not only of economic importance but also of significance for the environment and health. Hydrogen production is exemplified in this work by using bismuth sulfide (Bi2S3) sandwiched in between zinc sulfide (ZnS) and zinc oxide (ZnO) as dual-heterojunction photoelectrode to photoelectrochemically extract H2 from sulfide- and sulfite-containing wastewater, which is emitted in enormous quantities from the petrochemical industries. The H2 evolution rate over the ZnS/Bi2S3/ZnO photoelectrode under solar illumination amounts to 112.8 μmol cm–2 h–1, of which the photocurrent density in the meantime reaches 10.7 mA cm–2, by far exceeding those reported for additional Bi2S3-based counterparts in the literature. Such superior performance is ascribed on one hand to the broadband sunlight-harvesting ability of Bi2S3 that gives rise to respectable photoexcited electron–hole pairs. These photogenerated charge carriers are subsequently rectified by the built-in electric field at the ZnS/Bi2S3 and Bi2S3/ZnO heterojunctions to flow in the opposite directions to well circumvent the recombination losses and, most importantly, in turn contribute substantially to the H2 evolution reaction.
In this study, a graphene-based dual-photoelectrode photocatalytic fuel cell (PFC) system, incorporating n-type ZnO photoanode and p-type Cu 2 O photocathode, has been meticulously designed and fabricated to achieve concurrent organic pollutant decomposition and electricity production. The rGO-ZnO｜rGO-Cu 2 O PFC system displayed superior photoelectrocatalytic performance, surpassing the comparative FTO-based PFC system. Notably, it achieved power density of 22.23 μW cm −2 maximumly, tetracycline hydrochloride (TCH) degradation efficiency of 74.0 % within 120 min, and exhibited long-term stability. This enhanced performance can give the credit to the larger active areas generated by the in-situ growth of photocatalytic materials in layered microstructure of graphene films, as well as the rapid electron transfer within graphene films. This study underscores the potential application of graphene films as electrode substrate materials, and introduces a strategy for achieving the diversification and optimization of electrode substrate material selection, ultimately facilitating the development of more efficient PFC systems.
Charge recombination is an important factor that limits the cell efficiency of quantum dot sensitized solar cells (QDSSCs). Herein, we report a facile way to improve the cell performance of CdSe sensitized ZnO QDSSC by overcoating a thin layer of ZnSe on CdSe/ZnO film through a successive ionic layer adsorption and reaction (SILAR) procedure. Photovoltaic investigations indicate that ZnSe overcoating can increase photocurrent and photovoltage of the cell, resulting in significant enhancement of the cell efficiency, which is much better than the widely used traditional ZnS material. The superior role of ZnSe overcoating is ascribed to its large inhibition of charge recombination loss owing to its suitable band structure, efficient passivation of ZnO and CdSe QDs as well as its small lattice mismatch with CdSe that leads to the large decrease of surface/interface defects in CdSe/ZnO photoanode . This finding provides an alternative efficient way to enhance the cell performance of ZnO based QDSSC by suppressing the charge recombination.
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