Microcatalysis in Photonic Crystal Fibers

Microcatalysis in Photonic Crystal Fibers

Author: Lois O'Leary

Optofluidic microdevices where light and fluids can interact for spectroscopic or photoactivation purposes are excellent platforms for photocatalysis and in situ reaction analysis. Photonic crystal fiber (PCF) has emerged as a new class of optical fiber for such devices.

Bastian J. M. Etzold and co-workers, Excellence Cluster Engineering of Advanced Materials, Erlangen, Germany, describe how both homo- and heterogeneous catalysis are performed with ultra-high power densities at moderate laser powers in the new PCF design of cladding surrounding a waveguide of small core diameter (pictured). Chemical samples are introduced to micrometer-sized holes in the PCF, overcoming the limited light-sample interaction or leakage of light typical to conventional optical fibers.

Schematic of a conventional 1 cm cuvette and a 20 μm core kagomé hollow-core PCF (not to scale).

Dispersed catalytic systems in PCF enable advanced oxidation processes such as the degradation of organic pollutants. PCF-immobilized catalysts, for example in the supported ionic liquid phase, catalyze key reactions such as hydroformylations, hydrogenations, carbonylation, hydroaminations, Friedel-Crafts alkylations, and the water-gas shift reaction. Metal nanoparticles can also be deposited in PCFs, for example, gold or silver are used to form surface-enhanced Raman scattering-active fibers.

Ingeniously, this design, compared to the conventional centimeter-sized cuvettes, also improves quantitative photospectroscopic reaction analysis, enabling the detection of analytes in ultra-low concentrations.

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