A Paper-Based Microfluidic Methanol Fuel Cell Catalyzed By Ni-Co@LTA Electrocatalyst for Micro-Nano Power Systems

Abstract

Sustainable energy generation has recently gained popularity due to the rising energy demand and environmental concerns caused by conventional non-renewable energy sources. In the context of portable electronics, and microsystems all would require fully integrated, dependable power generation. In this regard, paper-based microfluidic fuel cells (PMFC), have drawn significant attention. By utilizing the inherent properties of paper substrate and microfluidic reactant streams, this fuel cell device takes away the requirement of any membranes or external pumps that are necessary for conventional FCs. In co-laminar flow, where PMFCs work, a unique diffusive mixing area serves as a pseudo-membrane by preventing the convective mixing of two reactants. The reactants flow by capillary action with the aid of an absorbent pad. While the ions transport across the channel through the mixing zone. This not only makes the pumping of fluids into paper-based systems simpler, but also provides numerous other benefits such as cost-effectiveness, simplicity in manufacturing, ease of disposal, and portability over traditional FCs. In this work, we synthesized a Ni-Co catalyst encapsulated within zeolite 4A (also known as LTA) via a hydrothermal synthesis route. The resulting catalyst exhibited better catalytic activity of 12.1 mA cm-2 at 1.12 V vs Ag/AgCl and retained remarkable stability (~77%) even after 1000 cycles CV test in 0.1 M KOH + 1 M methanol. By utilizing this catalyst as anode and Pt/AC (5 wt%) as cathode, we demonstrate a Y-shaped membraneless PMFC using Whatman filter paper grade 41 as paper substrate. It has been shown that the device can deliver power densities in the range of 2 - 10 mW cm-2 (Fuel: methanol, Oxidant: KMnO4), and can retain power output for at least 30 min. Additionally, the power of the cell can easily be raised by connecting two or more cells in series, making these PMFCs suitable for micro/nano power generation systems.Keywords: Fuel cell, Microfluidic, Paper substrate, Co-laminar flow, Zeolite 4A.