s Photocatalytic H 2 O 2 production represents a sustainable and promising avenue for energy and environment. Photoproduction of H 2 O 2 in seawater is potentially an alternative to meet the needs of H 2 O 2 utilization in ocean, while with challenges of competitive ions influence and unsolved photocatalytic mechanism. Herein, we constructed a S-scheme heterojunction with the lamellated WO 3 coated CdS semiconductors for photoproduction of H 2 O 2 in actual seawater. Fragmented WO 3 uniformly spread on surface of dispersed CdS spheres by two steps including calcination and ultrasound. Photocatalyst achieved considerable 1.00 mmol·g cat −1 ·h −1 of H 2 O 2 productivity in seawater without electron-proton donors and pure O 2 , 9.3 % of apparent quantum yield (AQY), as well as good reusability. A co-catalysis concept was proposed to explore specific role of ions in seawater on H 2 O 2 photoproduction. S-scheme heterojunction contributed to migration of electrons and holes on interface between WO 3 and CdS, and further promoted separation of photocarriers, and further opened another channel for H 2 O 2 generation. Accumulated electrons in conduction band (CB) of CdS involved in the main route of two-electron reduction of O 2 for H 2 O 2 production, also promoted generation of •O 2 - for opening the auxiliary route. WO 3 /CdS heterojunction provided fundamentals and opportunities for H 2 O 2 production and applications in abundant seawater as a sustainable way.
Jun Wang,Yining Pan,Liangxing Jiang,Min Liu,Fangyang Liu,Ming Jia,Jie Li,Yanqing Lai
Copper ions are not only physiologically essential for life but also hazardous materials causing a series of neurodegenerative diseases. Photoelectrochemical (PEC) detection has attracted a large amount of focus as a potential strategy to develop Cu2+ ion sensors. However, relatively low photocurrent signals with poor antidisturbance ability and the limited concentration range have prevented its practical applications. Here, we designed a WO3/CdS heterojunction photoanode for the PEC determination of Cu2+ in aqueous solution through a simple two-step chemical bath deposition method. The obtained WO3/CdS photoanode had a nanoplate morphology and showed an enhanced photoresponsivity with a photocurrent density of 1.5 mA/cm2 at 1.23 V versus RHE under illumination. Naturally, it exhibited a low detection limit (0.06 μM) and wider range (0.5 μM to 1 mM) for Cu2+ PEC detection first, suggesting that the WO3/CdS heterojunction photoanode is a promising tool to monitor copper pollution in natural environments.
Jianing Li,Juan Chen,Yanhui Ao,Xin Gao,Huinan Che,Peifang Wang
The construction of dual Z-scheme photocatalysts is an effective way to promote the separation and migration of electrons-holes as well as retain their high redox abilities. Herein, a distinctive dual Z-scheme photocatalyst based on phase junction WO 3 and CdS (CW) was successfully fabricated via hydrothermal method and in-situ precipitation process. The as-prepared materials showed the advantages of both phase junction and dual Z-scheme mechanism (promoted utilization of carriers and improved redox potential). As a result, the k app value of 75CW (0.05237 min −1 ) was 29.8 times that of phase junction WO 3 (0.00176 min −1 ) and 2.9 times that of CdS (0.01799 min −1 ) in terms of imidacloprid (IMD) degradation. Trapping experiment and electron spin resonance (ESR) proved the dual Z-scheme mechanism, the key to significantly improve photocatalytic degradation efficiency of WO 3 /CdS nanocomposites. Combined the analysis of liquid chromatography-mass spectrometry (LC-MS) with density functional theory (DFT) calculation, rational degradation pathways of IMD were put forward in detail. This work is excepted to provide new horizons for the construction of dual Z-scheme system with phase junction and the photodegradation of IMD.
Taiping Hu,Pengfei Li,Jinfeng Zhang,Changhao Liang,Kai Dai
Cadmium sulfide (CdS) has demonstrated great promise in artificial photocataytic hydrogen (H 2 ) production. However, the serious photocorrosion hinders its effective interaction and real-life application. In this work, a typical direct Z-scheme WO 3 /CdS-diethylenetriamine (CdS-DETA) composite has been designed via facile in-situ solvothermal method, which exhibits excellent H 2 production properties in visible light region. In this system, the inorganic–organic CdS-DETA nanobelts (NBs) possess enough active sites and large surface area for the encouraging nanojunction structure information. Furthermore, we also systematically calculated energy band structure and investigated charge transfer of the WO 3 /CdS-DETA by PL and photocurrent test, the results demonstrated that the suitable band gap matching between CdS-DETA and WO 3 and high redox potential improve the separation of photogenerated holes and electrons, restraining intrinsic photocorrosion of CdS as well as improving the photocatalytic activity. 5%WO 3 /CdS-DETA presented the most outstanding H 2 evolution rate (15522 μmol g −1 h −1 ), which is twice higher than that of pure CdS-DETA. WO 3 /CdS-DETA composites also presented high stability after three recycle H 2 production experiment. Finally, direct Z-scheme photocatalytic mechanism is calculated.
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