Hydrogen (H2) production from renewable biomass resources plays a significant role in solving the shortage of fossil energy;hence, there is an interest in investigating alternative, cleaner processes. This work intends to study the photocatalytic production of hydrogen from D-(+)-Glucose by using different groups of catalysts that have been prepared (M2+ = Zn, Mg and Ni) M2+/Ti4+ Al3+-LDHs (layered double hydroxides). It is then loaded Pd on the catalyst, and the effect of the composite catalyst, layered double hydroxides, is measured. After calcining, the catalyst for the conversion of Layered Double Hydroxides (LDHs) to Layered Double Oxides (LDOs) is used to produce hydrogen gas from glucose. Photocatalytic reforming of glucose-derived compounds is an efficient method for the production of hydrogen. The purpose is to study the effect of metal ions on layered double oxide (LDO) materials by loading Pd and investigate hydrogen production from glucose. The metal cations in the layer were distributed through the preparation of the catalyst process by ion and atom scale between the layers, which were dispersed systematically, as well as the controlled component catalysis. This process shows that ZnTiAl-LDO had the best effect as a catalyst in producing hydrogen compared to NiTiAl-LDO and MgTiAl-LDO.
Photocatalysis is a promising approach for solar energy conversion and environmental remediation, which has garnered increasing attention. Advanced in situ characterization techniques enable real-time observation of dynamic changes in catalyst structure, charge transfer, and surface species during photocatalytic reactions, which is crucial for understanding the relationship between photocatalyst structure and activity. This review summarizes the main applications of in situ characterization techniques in photocatalysis, discusses their contributions to optimizing photocatalyst performance for enhanced solar energy conversion and environmental applications, provides guidance for designing in situ experiments to understand catalytic mechanisms, and presents an outlook on the future development of in situ characterization techniques in photocatalysis.
HU MiaoJumanah ALHARBIZHANG HuabinHassan S.AI QAHTANIFENG Chengyang
Semi-heterogeneous photocatalysis has emerged as a powerful and productive platform in organic chemistry,which provides mild and eco-friendly conditions for a diverse range of bond-forming reactions.The synergy of homogeneous catalysts and heterogeneous catalysts inherits their main advantages,such as higher activities,easy separation and superior recyclability.In this review,we summarize the recent advances in recyclable semi-heterogenous protocols for the light promoted bond-forming reactions and identify directions for future research according to the different photocatalysts/metal/redox catalysts involved.Notably,this review is not a comprehensive description of reported literature but aim to highlight and illustrate key concepts,strategies,reaction model,reaction conditions and mechanisms.
Jia-Cheng HouWei CaiHong-Tao JiLi-Juan OuWei-Min He
Crystalline carbon nitride(CCN)has emerged as a highly promising semiconductor photocatalyst with unique properties,such as enhanced charge migration rate,reduced carrier recombination probability,narrow band gap and improved light-harvesting efficiency,which are suitable for a wide range of applications in solar-to-chemical conversion,energy storage,therapeutic and environmental pollution degradation.In the past few years,there has been an increasing number of reviews on CCN materials.However,most of these reviews mainly focus on synthesis methods,modification and applications,with less emphasis on the relationship between structures and properties,as well as on indepth exploration of the crystalline structure.The electronic instability of CCN presents challenges for conventional characterization techniques to directly and thoroughly investigate the relationship between its intrinsic atom structure and photocatalytic performance.This mini-review not only highlights the progress in CCN-based photocatalysts,with a focus on molten-salt synthesis(including solid-salt-induced crystallization),but also emphasizes the atomic structure characterization by specifically introducing the differential phase contrast(DPC)scanning transmission electron microscopy(STEM)technique,which is essential for enhancing our understanding of the crystal structure and photocatalytic mechanisms of CCNs.Additionally,the review outlines the photocatalytic performance and puts forward potential challenges on CCN studies.This review will provide a clearer understanding of the relationship in developing precise customization strategies for CCN materials and ultimately explain the regularity and specificity of the enhanced performance in targeted photocatalytic systems.
Covalent organic frameworks(COFs)based photocatalysts utilizing infrared light remains unexplored due to the limitation of electronic absorption.Herein,two novel two-dimensional(2D)polyimide-linked phthalocyanine COFs,namely MPc-DPA-COFs(M=Zn/Cu),were prepared from the imidization reaction of metal tetraanhydrides of 2,3,9,10,16,17,23,24-octacarboxyphthalocyaninato(M(TAPc))with 9,10-diphenyl anthracene(DPA).Both COFs possess highly crystalline eclipsed AA stacking structure with neighboring layer distance of 0.33 nm on the basis of powder X-ray diffraction analysis and high-resolution transmission electron microscopy.Effective π–π interaction between phthalocyanine chromophores in neighboring layers of 2D COFs leads to significant bathochromic-shift of narrow Q band from 697 nm for M(TAPc)to the infrared light absorption range of 760–1000 nm for MPc-DPA-COFs according to solid UV-vis diffuse reflectance spectra.This endows them in particular ZnPc-DPA-COF with excellent reactive oxygen species of•O_(2)^(–)and 1O_(2) generation activity under infrared light radiation(λ>760 nm)based on the electron spin resonance spectroscopy measurement,in turn resulting in the excellent photocatalytic capacity towards oxidation of sulfides under infrared light radiation.Corresponding quenching experiments reveal the contribution of both•O_(2)^(–)and 1O_(2) to the oxidation of sulfides,but the former•O_(2)^(–)species plays a leading role in this photocatalytic process.The present result not only provides a new efficient infrared light photocatalyst but also unveils the good potentials of phthalocyanine-based COFs in photocatalysis.
The mass production and widespread use of Pharmaceuticals and Personal Care Products(PPCPs)have posed a serious threat to the water environment and public health.In this work,a green metal-based Metal Organic Framework(MOF)Bi-NH_(2)-BDC was prepared and characterized,and the adsorption characteristics of Bi-NH_(2)-BDCwere investigated with typical PPCPs-diclofenac sodium(DCF).It was found that DCF mainly covered the adsorbent surface as a single molecular layer,the adsorption reaction was a spontaneous,entropyincreasing exothermic process and the adsorption mechanisms between Bi-NH_(2)-BDC and DCF were hydrogen bonding,π-πinteractions and electrostatic interactions.In addition,Bi-NH_(2)-BDC also had considerable photocatalytic properties,and its application in adsor-bent desorption treatment effectively solved the problem of secondary pollution,achieving a green and sustainable adsorption desorption cycle.
Xiaohui HeChun ChangLiping YangYanrong CaiQiong Wang
Photocatalytic oxidation through semiconductor photocatalysis is an efficient and green technology for pollutant removal,which has been widely applied to degrade volatile organic chemicals under ambient conditions.However,most of reports focus on the reduction of VOCs concentration while ignore the generation of toxic intermediates,as well as the corresponding secondary pollution.Therefore,it is necessary to further explore how to timely achieve efficient and deep oxidation of VOCs.In this review,we undertake a detailed analysis of photocatalytic degradation of toluene,a representative compound of aromatic hydrocarbon VOCs,and identify the most capable phenolized pathway governed by hydroxyl radicals(·OH).With this pathway,no toxic intermediate like benzene is produced during the photocatalysis.The driving factor,oxygen vacancy(OV),for fueling the generation of ·OH is highlighted and the specific approaches including doping engineering and co-catalyst loading that can create rich OVs in semiconductor photocatalysts are described.Furthermore,the challenges and opportunities faced by the phenolized pathway in the future development are prospected.
The production of renewable methanol(CH_(3)OH)via the photocatalytic hydrogenation of CO_(2) is an ideal method to ameliorate energy shortages and mitigate CO_(2) emissions:however,the highly selective synthesis of methanol at atmospheric pressure remains challenging owing to the competing reverse water-gas shift(RWGS)reaction.Herein,we present a novel approach for the synthesis of CH_(3)OH via photocatalytic CO_(2) hydrogenation using a catalyst featuring highly dispersed Au nanoparticles loaded on oxygen vacancy(OV)-rich molybdenum dioxide(MoO_(2)),resulting in a remarkable selectivity of 43.78%.The active sites in the Au/MoO_(2) catalyst are high-density Au-oxygen vacancies,which synergistically promote the tandem methanol synthesis via an initial RWGS reaction and subsequent CO hydrogenation.This work provides comprehensive insights into the design of metal-vacancy synergistic sites for the highly selective photocatalytic hydrogenation of CO_(2) to CH_(3)OH.
Xingjuan LiYuhao GuoQinhui GuanXiao LiLulu ZhangWeiguang RanNa LiTingjiang Yan