Mesoporous Decoration of Freestanding Palladium Nanotube Arrays Boosts the Electrocatalysis Capabilities toward Formic Acid and Formate Oxidation

Abstract

IntroductionWith the growing demand for green energy technologies, direct formic acid fuel cells (DFAFCs) [1,2] and direct formate fuel cells (DFFCs) [3,4] have drawn tremendous attention as promising clean energyconversion systems. Formic acid oxidation (FAO) and formate oxidation reaction (FOR) electrocatalysts largely determine the performance of DFAFCs and DFFCs; therefore, developing high-performance catalysts for FAO/FOR is critical for relevant fuel cell commercialization. [5][6][7] As an alternative to traditional platinum-based catalysts, [8] palladium-based catalysts for FAO/FOR attract increasing interest due to their relatively low cost, high activity in directly oxidizing fuels at relatively low potentials and high resistance to carbon monoxide poisoning. [9][10][11][12][13][14] Aiming at the superior FAO/FOR electrocatalysis capabilities with minimum noble metal usage, rationally establishing nanoscale architectures for Pd-based catalysts possessing high electrochemical active surface area, large areal density of catalytically active sites, and facile kinetics of substance exchange is a key step. [15][16][17][18][19][20][21] Achievement of all three qualities simultaneously is a significant challenge since these qualities are, to some extent, antagonistic. Nanosizing and porosity generation for bulk palladium catalysts are effective methodologies to increase the electrochemical active surface area and active site population. [22,23] However, substance transport becomes sluggish due to the low accessibility of the tortuous nanoporosity and the closed 3D geometric nanostructures. It is widely acknowledged that 1D nanotubes are a suitable nanoarchitecture for facile substance transport. [24][25][26][27][28] An open tube with a large diameter is highly beneficial for ion accessibility and diffusion. Various wet chemical methods have been attempted for palladium nanotube synthesis. [29][30][31] Nevertheless, most of these nanotube products were collected as piled-up powders. The inevitable nanotube agglomeration wastes the active surface area and diminishes the exposed catalytic active sites.The agglomeration issue could be effectively alleviated if the Pd nanotubes were aligned in parallel on the current collector substrate to form perpendicular Pd nanotube arrays (PdNTA).Fabricating high-performance electrocatalysts is the most critical step in commercializing direct formic acid or formate fuel cells. In this work, a dualtemplate electrodeposition method is used to create freestanding mesoporosity decorated palladium nanotube arrays (P-PdNTA) as a bifunctional electrocatalyst toward formic acid and formate oxidation (FAO/FOR). The phytantriol-based soft template modifies the superficial chemistry of aluminum anodic oxide inner surfaces, thereby facilitating the regulated electrodeposition of highly stable palladium nanotubes. The sacrifice of the soft template generates substantial mesoporosity on the nanotubes, resulting in a 189% increase in the electrochemically active surface area with respect to t...

Advances in the development of power supplies for the Internet of Everything

“…The complicated replacement of batteries is challenging due to the large number of batteries (millions and billions) in the IoE system . Usually, the lifetime of batteries is determined by the temperature, state‐of‐charge, magnitude of load currents, self‐discharge, and so on, which is mainly affected by the electrode and electrolyte materials as well as the interfacial matching between them . The service life of some typical commercial batteries is shown in Table .…”

“…48 Usually, the lifetime of batteries is determined by the temperature, state-of-charge, magnitude of load currents, self-discharge, and so on, which is mainly affected by the electrode and electrolyte materials as well as the interfacial matching between them. 49,50 The service life of some typical commercial batteries is shown in Table 1. 51 Owing to the high ionic conductivity retention capability and excellent interfacial properties, liquid-electrolyte-based power sources tend to exhibit longer lifetimes.…”

Battery Technologies for Grid-Level Large-Scale Electrical Energy Storage

“…As a just-in-time supply system, GLEES plays a fundamental role in avoiding excessive power generation capacity to meet short-term peak electricity need, which is mainly oriented to alleviate the power supply gap of the grid, improve the utilization efficiency of power generation equipment, avoid frequent start and stop of the thermal power unit, reduce the investment in power grid construction, and ensure the safe and stable operation of the power grid system. So far, several types of energy storage approaches have been investigated and explored, such as secondary battery technologies and supercapacitors, flow batteries, fuel cells, flywheels, compressed air energy storage, thermal energy storage, and pumped hydroelectric power [2][3][4][5][6][7][8][9]. Among them, traditional energy storage technologies usually have low energy efficiency, require immense capital investment, and have location-dependent problems.…”

Tunable Periodically Ordered Mesoporosity in Palladium Membranes Enables Exceptional Enhancement of Intrinsic Electrocatalytic Activity for Formic Acid Oxidation

“…Creating mesoporosity is known as an effective strategy to increase the exposed surface area of bulk catalysts. [10][11][12][13][14][15] Nonetheless, surface amplification can barely lead to a proportional enhancement in catalytic capability towards FAO due to the low coefficient of utilization for the surface area. This phenomenon is expected considering the real scenario in FAO electrocatalysis systems, where the accessibility, transport efficiency and exchange kinetics of the species (e.g., HCOOH, CO 2 ) within the catalyst bulk are of vital importance for the electrocatalytic activity.…”