A review on photo-, electro- and photoelectro- catalytic strategies for selective oxidation of alcohols

Traditional conversion of alcohols into carbonyl compounds exists a few drawbacks such as harsh reaction conditions,production of large amounts of hazardous wastes,and poor selectivity.The newly emerging conversion approaches via photo-,electro-,and photoelectro-catalysis to oxidize alcohols into high value-added corresponding carbonyl compounds as well as the possible simultaneous production of clean fuel hydrogen(H_(2))under mild conditions are promising to substitute the traditional approach to form greener and sustainable reaction systems and thus have aroused tremendous investigations.In this review,the state-of-the-art photocatalytic,electrocatalytic,and photoelectrocatalytic strategies for selective oxidation of different types of alcohols(aromatic and aliphatic alcohols,single alcohol,and polyols,etc.)as well as the simultaneous production of H_(2) in certain systems are discussed.The design of photocatalysts,electrocatalysts,and photoelectrocatalysts as well as reaction mechanism is summarized and discussed in detail.In the end,current challenges and future research directions are proposed.It is expected that this review will not only deepen the understanding of environmentally friendly catalytic systems for alcohol conversion as well as H_(2) production,but also enlighten significance and inspirations for the follow-up study of selective oxidation of various types of organic molecules to value-added chemicals.

Photocatalytic one-step synthesis of Ag nanoparticles without reducing agent and their catalytic redox performance supported on carbon

Synthesis of silver nanoparticles(Ag NPs) with state-of-the-art chemical or photo-reduction methods generally takes several steps and requires both reducing agents and stabilizers to obtain NPs with narrow size distribution.Herein, we report a novel method to synthesize Ag NPs rapidly in one step, achieving typical particle sizes in the range from 5 to 15 nm.The synthesis steps only involve three chemicals without any reducing agent: AgNO3 as precursor, polyvinylpyrrolidone(PVP) as stabilizer, and AgCl as photocatalyst.The Ag NPs were supported on carbon and showed excellent performance in thermal catalytic pnitrophenol reduction and nitrobenzene hydrogenation, and as electrocatalyst for the oxygen reduction reaction.

Highly dispersed Pd clusters/nanoparticles encapsulated in MOFs via in situ auto-reduction method for aqueous phenol hydrogenation

In this work,a novel in situ auto-reduction strategy was developed to encapsulate uniformly dispersed Pd clusters/nanoparticles in MIL-125-NH_(2).It is demonstrated that the amino groups in MIL-125-NH_(2)can react with formaldehyde to form novel reducing groups(-NH-CH_(2)OH),which can in situ auto-reduce the encapsulated Pd^(2+)ions to metallic Pd clusters/nanoparticles.As no additional reductants are required,the strategy limits the aggregation and migration of Pd clusters and the formation of large Pd nanoparticles via controlling the amount of Pd^(2+)precursor.When applied as catalysts in the hydrogenation of phenol in the aqueous phase,the obtained Pd(1.5)/MIL-125-NH-CH_(2)OH catalyst with highly dispersed Pd clusters/nanoparticles with the size of around 2 nm exhibited 100%of phenol conversion and 100%of cyclohexanone selectivity at 70℃ after 5 h,as well as remarkable reusability for at least five cycles due to the large MOF surface area,the highly dispersed Pd clusters/nanoparticles and their excellent stability within the MIL-125-NH-CH_(2)OH framework.