Fabrication of Flexible Nanoporous Platinum Films Via One-Pot Liquid Crystal Templated Synthesis

Abstract

Nanoporous platinum (NPP) thin films are crucial for applications in electrocatalysis, fuel cells, nanophotonics, and gas sensing. Conventional fabrication methods, such as dealloying, often leave residual elements that degrade the performance of the NPP thin films in applications such as electrocatalysis. In this study, for the first time, we introduce a novel method to fabricate ultrapure, flexible, large-area NPP thin films through a one-pot, liquid crystal-templated synthesis. A hexagonal lyotropic liquid crystal (LLC) phase, composed of a strong acid, a nonionic surfactant, water, and hexachloroplatinic acid, serves as a template. The LLC films, prepared with hexachloroplatinic acid concentrations of 0.1-0.5 M, exhibit distinct optical textures under a polarizing optical microscope and display low-angle diffraction patterns when analyzed with an X-ray diffractometer. Calcination at 450 degrees C yields ultrapure, conductive, and black colored NPP films. Importantly, we fabricate freestanding NPP thin films and successfully transfer them onto both rigid and flexible substrates. Bending tests reveal that a four-layer flexible NPP film having a thickness of around similar to 174 nm maintains a stable sheet resistance (similar to 30 ohm/sq) after several hundred bend cycles (1000 cycles). These findings highlight the potential of ultrapure NPP films with high nanopore and ligament density for applications in electrocatalysis, fuel cells, gas sensors, broadband absorbers, bioelectronics, and flexible electronics.