Noble-metal free plasmonic nanomaterials for enhanced photocatalytic applications—A review

Plasmonic nanomaterial catalysis is currently at the frontier of photocatalysis,overcoming the limitations of wide bandgap semiconductors for light absorption.Its localized surface plasmon resonance(LSPR)properties allow broad ultraviolet-visible-near infrared ray(UV-vis-NIR)absorption,making it an ideal material for solar energy conversion.Most plasmonic nanostructures rely on precious metals.Although noble metal plasmonic nanomaterials have proven to be one of the strategies for enhancing photocatalytic activity,their expensive cost and limitations in light absorption range have hindered their practical application.As a result,noble-metal free plasmonic nanomaterials have risen to the top of the research priority list.Therefore,this paper reviews the fundamental principles and classification of the LSPR effect of noble-metal free plasmonic nanomaterials in photocatalytic and their recent applications in hydrogen generation,carbon dioxide reduction,and pollutant degradation.Specific cases elucidate the possible working mechanism of enhanced photocatalysis by noble-metal free plasmonic nanomaterials.Finally,the challenges and future opportunities for noble-metal free plasmonic nanomaterials in energy conversion and storage are discussed and envisioned.

Advanced noble-metal-free bifunctional electrocatalysts for metal-air batteries

The sluggish reaction kinetics at the oxygen cathode is one of the important issues hindering the commercialization of the metal-air batteries.Although the noble metal can be used as the high-efficiency electrocatalyst to solve the problems to some extent,the high cost and scarcity of these noble-metal catalysts have limited their application in electrocatalysis.In this review,we discussed the mecha-nisms of the ORR and OER,and proposed the principles for the bifunctional electrocatalysts firstly,and then the state-of-the-art bifunctional catalysts,including carbon-based materials and transition-metal-based materials.On the basis of that,the self-supporting 3D noble-metal-free bifunctional ORR/OER catalysts were also discussed.Finally,the perspectives for the bifunctional electrocatalysts were discussed.

High efficient catalytic oxidation of 5-hydroxymethylfurfural into 2,5-furandicarboxylic acid under benign conditions with nitrogen-doped graphene encapsulated Cu nanoparticles

Selective oxidation of 5-hydroxymethylfurfual(HMF) to 2,5-furandicarboxylic acid(FDCA) as a bioplastics monomer is efficiently promoted by a simple system without noble-metal and base additives. In this work, graphene oxide(GO) was first synthesised by an electrochemical method with flexible graphite paper(FGP) as start carbon material, then, nitrogen-doped graphene(NG) layers encapsulated Cu nanoparticles(NPs) was prepared by one-step thermal treatment of GO supported Cu2+ in flowing NH3 atmosphere. Compared with NG supported Cu NPs prepared by the traditional impregnation method, enhanced catalytic activity was achieved over Cu/NG and an FDCA yield of 95.2% was achieved under mild reaction conditions with tert-butylhydroperoxide(t-BuOOH) as the oxidant. Control experiments with different catalysts and different addition procedure of t-BuOOH showed the yield of HMF and various intermediates during reaction. From the changing of intermediates concentrations and reaction rates, a reaction pathway through HMF-DFF-FFCA-FDCA was proposed. This work gives a more convenient, more green,more economical and effective method in encapsulated metal NPs preparation and high selectivity in HMF oxidation to FDCA under mild conditions.

Crystal Growth Kinetics and Size Controls——Ⅰ.for Some Anode Active Oxides

RuO2,IrO2 and PdO are the most frequently employed active oxides in titanium anode coatings,so studies on the kinetics of their crystal-growth are important for anode material preparations.In this paper,the particle growths of RuO2,IrO2 and PdO with increased temperature were discussed.The least-squares method was used to fit the kinetic data.As a result,the two-stage phenomena are found in all three noble material systems.The linear regression equations are correct both for the first and second stages.It is suggested that based on the corresponding kinetics equation Ln D =-QL/kT ＋ a,the sizes of oxide particles can be controlled for the three noble oxides.