H2O INSIGHTS LLC — National Aeronautics and Space Administration STTR Phase I: T7

Description

Photoelectrocatalytic processes (PECs) integrate the principles of photocatalysis (PC) and electrocatalysisnbsp;to improve the generation and stability of charge carriers, making them an effective way to produce H2 and H2O2. Reactor design is critical for optimal energy efficiency in activating advanced photocatalysts. Low energy efficiency in current PEC flat-plate reactor designs is due to light attenuation by glass materials and water, and limited surface area for photo-excitation. To overcome these challenges, we propose a new architecture called the optoelectrode that utilizes visible wavelength (gt;400 nm) light emitting diodes (LEDs) to launch light into one end of durable polymer optical fibers (POFs). The POFs side-emit light to activate non-platinum group element-based nanomaterials (NMs) embedded in porous polymers on the POF surface. Our reactor can house single or bundles of gt;100 POF optoelectrodes (~1.5 mm diameter amp; 10 to gt;50 cm lengths)nbsp;and we propose two architectures for producing resources from water.In previous work, we have demonstratednbsp;that:A cathodic optoelectrode produces H2 from water using two NMs embedded within porous layer of the POF surface, creating a PEC-POF system that generates H2 on the fiber surface.A photocatalytic optoelectrode withnbsp;a single NM (iron-based metal organic framework (MOF)) embedded within porous layer of the POF surface, producesnbsp;gt;1 wt% H2O2 from water.nbsp;Compared to flat glass-plate architectures with the same NM, POF optoelectrodes achieve gt;700% larger catalyst surface areanbsp;and gt;300% better incident photon-to-current efficiency (IPCE) with lower energy input. POF is also agnostic to nanomaterial type, enabling deposition of tunable nanomaterials for specific wavelengths using LED or polychromatic light. Bundling large numbers (ngt;100) of POF optoelectrodes enables higher packing geometries (i.e., m2 catalyst surface per m3 reactor volume) than flat-electrode PEC reactors, minimizing reactor size and power requirements.