An organic visible-photocatalytic-adsorbence mechanism to high-efficient removal of heavy metal antimony ions

Purification of emerging heavy metal antimony contaminated water based on advanced ingenious strategies.An activated modified coconut shell charcoal(CSC)was synthesized and evaluated as a substrate-supported loaded organic photovoltaic material,PM6:PYIT:PM6-b-PYIT,to prepare a surprisingly highly efficient,stable,environmentally friendly,and recyclable organic photocatalyst(CSC–N–P.P.P),which showed excellent effects on the simultaneous removal of Sb(Ⅲ)and Sb(Ⅴ).The removal efficiency of CSC-N-P.P.P on Sb(Ⅲ)and Sb(Ⅴ)reached an amazing 99.9%in quite a short duration of 15 min.At the same time,under ppb level and indoor visible light(~1 W m^(2)),it can be treated to meet the drinking water standards set by the European Union and the U.S.National Environmental Protection Agency in 5 min,and even after 25 cycles of recycling,the efficiency is still maintained at about 80%,in addition to the removal of As(Ⅲ),Cd(Ⅱ),Cr(Ⅵ),and Pb(Ⅱ)can also be realized.The catalyst not only solves the problems of low reuse rate,difficult structure adjustment and high energy consumption of traditional photocatalysts but also has strong applicability and practical significance.The pioneering approach provides a much-needed solution strategy for removing highly toxic heavy metal antimony pollution from the environment.

Progress in organic photocatalysts

Organic materials have advantages of diversity,ease of functionality, self-assembly, etc. The varied mechanistic pathways also make it conceivable to design an appropriate photocatalyst for an identical reaction. From this perspective, organic photocatalysts find wide applications in homogeneous, heterogeneous photocatalysis and photoelectrochemical（PEC） solar cells. In this review, the form of the employed organic photocatalysts ranging from molecules, supported molecules, to nanostructures or thinfilm aggregates will be firstly discussed. Rational design strategies relating to each form are also provided, aiming to enhance the photoenergy conversion efficiency. Finally,the ongoing directions for future improvement of organic materials in high-quality optoelectronic devices are also proposed.

Organic photocatalysts:From molecular to aggregate level

Organic semiconductors(OSCs)have the advantages of tunable molecular structures,suitable band gaps,and exceptional optoelectronic properties.The π-π stacking ability of OSCs also leads to appealing molecular stacking structure,function,and stability.So far,organic photocatalysts have engaged in homogeneous or heterogeneous photocatalysis in the form of free molecules,supported molecules,or nanostructures.Meanwhile,researches on organic photocatalysts have expanded from small organic molecules to the organic macromolecules,as well as their various nanostructures and nanocomposites including isolated zero-dimensional(0D),one-dimensional(1D),two-dimensional(2D),three-dimensional(3D)nanostructures,and their combinations.Therefore,many versatile strategies have been explored to improve photocatalytic ability and practicality either from molecular synthetic modification,crystal,or interface engineering.In this review,we first discuss the photophysical and photochemical processes of organic photocatalysts that govern the ultimate photocatalytic efficiency;we then summarize different forms of organic photocatalysts,their rational design strategies,and mechanistic pathways,as well as their applications in H_(2) evolution,CO_(2) reduction,and environmental purification,aiming to highlight the structure/property relationships;we lastly propose ongoing directions and challenges for future development of organic photocatalysts in real use.

Tailorable carbazolyl cyanobenzene-based photocatalysts for visible light-induced reduction of aryl halides

Herein,a series of carbazolyl cyanobenzene(CCB)-based organic photocatalysts with a broad range of photoredox capabilities were designed and synthesized,allowing precise control of the photocatalytic reactivity for the controllable reduction of aryl halides via a metal-free process.The screened-out CCB(5CzBN),a metal-free,low-cost,scalable and sustainable photocatalyst with both strong oxidative and reductive ability,exhibits superior performance for both dehalogenation and C—C bond-forming arylation reactions.