scholarly journals Controlled Biosynthesis of ZnCdS Quantum Dots with Visible-Light-Driven Photocatalytic Hydrogen Production Activity

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1357
Author(s):  
Shiyue Qi ◽  
Yahui Miao ◽  
Ji Chen ◽  
Huichao Chu ◽  
Bingyang Tian ◽  
...  

The development of visible-light-responsive photocatalysts with high efficiency, stability, and eco-friendly nature is beneficial to the large-scale application of solar hydrogen production. In this work, the production of biosynthetic ternary ZnCdS photocatalysts (Eg = 2.35–2.72 eV) by sulfate-reducing bacteria (SRB) under mild conditions was carried out for the first time. The huge amount of biogenic S2− and inherent extracellular proteins (EPs) secreted by SRB are important components of rapid extracellular biosynthesis. The ternary ZnCdS QDs at different molar ratios of Zn2+and Cd2+ from 15:1 to 1:1 were monodisperse spheres with good crystallinity and average crystallite size of 6.12 nm, independent of the molar ratio of Cd2+ to Zn2+. All the ZnCdS QDs had remarkable photocatalytic activity and stability for hydrogen evolution under visible light, without noble metal cocatalysts. Especially, ZnCdS QDs at Zn/Cd = 3:1 showed the highest H2 production activity of 3.752 mmol·h−1·g−1. This excellent performance was due to the high absorption of visible light, the high specific surface area, and the lower recombination rate between photoexcited electrons and holes. The adhered inherent EPs on the ZnCdS QDs slowed down the photocorrosion and improved the stability in photocatalytic hydrogen evolution. This study provides a new direction for solar hydrogen production.

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3437
Author(s):  
Andreas Rosenstiel ◽  
Nathalie Monnerie ◽  
Jürgen Dersch ◽  
Martin Roeb ◽  
Robert Pitz-Paal ◽  
...  

Global trade of green hydrogen will probably become a vital factor in reaching climate neutrality. The sunbelt of the Earth has a great potential for large-scale hydrogen production. One promising pathway to solar hydrogen is to use economically priced electricity from photovoltaics (PV) for electrochemical water splitting. However, storing electricity with batteries is still expensive and without storage only a small operating capacity of electrolyser systems can be reached. Combining PV with concentrated solar power (CSP) and thermal energy storage (TES) seems a good pathway to reach more electrolyser full load hours and thereby lower levelized costs of hydrogen (LCOH). This work introduces an energy system model for finding cost-optimal designs of such PV/CSP hybrid hydrogen production plants based on a global optimization algorithm. The model includes an operational strategy which improves the interplay between PV and CSP part, allowing also to store PV surplus electricity as heat. An exemplary study for stand-alone hydrogen production with an alkaline electrolyser (AEL) system is carried out. Three different locations with different solar resources are considered, regarding the total installed costs (TIC) to obtain realistic LCOH values. The study shows that a combination of PV and CSP is an auspicious concept for large-scale solar hydrogen production, leading to lower costs than using one of the technologies on its own. For today’s PV and CSP costs, minimum levelized costs of hydrogen of 4.04 USD/kg were determined for a plant located in Ouarzazate (Morocco). Considering the foreseen decrease in PV and CSP costs until 2030, cuts the LCOH to 3.09 USD/kg while still a combination of PV and CSP is the most economic system.


Author(s):  
Hanwen Xu ◽  
Jiawei Zhu ◽  
Pengyan Wang ◽  
Ding Chen ◽  
Chengtian Zhang ◽  
...  

Rational design and construction of high-efficiency bifunctional catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is crucial for large-scale hydrogen production by water splitting. Herein, by a...


2016 ◽  
Vol 52 (67) ◽  
pp. 10221-10224 ◽  
Author(s):  
Youn Jeong Jang ◽  
Jaegeon Ryu ◽  
Dongki Hong ◽  
Soojin Park ◽  
Jae Sung Lee

3D multi-stacked Si flakes have been successfully fabricatedviathe selective chemical reduction of natural clay on the strength of an inherently negative catalyst. Their solar-driven hydrogen production performance scored as the highest Si-based photocatalyst for hydrogen evolution with superior stability.


2007 ◽  
Vol 79 (11) ◽  
pp. 1917-1927 ◽  
Author(s):  
Akihiko Kudo

Photocatalytic water splitting is a challenging reaction because it is an ultimate solution to energy and environmental issues. Recently, many new powdered photocatalysts for water splitting have been developed. For example, a NiO (0.2 wt %)/NaTaO3:La (2 %) photocatalyst with a 4.1-eV band gap showed high activity for water splitting into H2 and O2 with an apparent quantum yield of 56 % at 270 nm. Overall water splitting under visible light irradiation has been achieved by construction of a Z-scheme photocatalysis system employing visible-light-driven photocatalysts, Ru/SrTiO3:Rh and BiVO4 for H2 and O2 evolution, and an Fe3+/Fe2+ redox couple as an electron relay. Moreover, highly efficient sulfide photocatalysts for solar hydrogen production in the presence of electron donors were developed by making solid solutions of ZnS with AgInS2 and CuInS2 of narrow band gap semiconductors. Thus, the database of powdered photocatalysts for water splitting has become plentiful.


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