Rising Again: Opportunities and Challenges for Platinum-Free Electrocatalysts

Abstract

It is well-known that platinum (Pt) is the best electrocatalyst currently available. However, its high cost and scarcity have hindered the commercialization of many green technologies that require the use of Pt electrocatalysts. To pave the way for mass production, the search for alternative electrocatalysts was initiated by researchers working in the fuel cell area, and it has been rapidly expanded to other energy applications in the past few years. Our discussion in this perspective starts with several reasons why Pt is the best electrocatalyst for many important electrochemical reactions such as the oxygen reduction reaction (ORR) and the hydrogen evolution reaction (HER). Along with a brief introduction of other novel metal electrocatalysts (ruthenium and iridium compounds) used for the oxygen evolution reaction (OER), this perspective highlights recent advances in the development of non-Pt electrocatalysts for dye-/quantum-dotsensitized solar cells (DSSCs/QDSSCs) and water-splitting systems. We identify the key materials in each area that have shown promising results for replacing Pt as an electrocatalyst and discuss their pros and cons. The possible mechanisms responsible for the observed improvements in performance are also discussed. While many materials have shown encouraging electrocatalytic activity, the long-term stability under a variety of operating conditions remains as a critical issue that must be addressed. An improved theoretical understanding is also required to accelerate the progress in this area. The main challenge is to identify the active sites and operating mechanisms in order to intelligently design and synthesize better and more cost-effective electrocatalysts.

A Co3O4-CDots-C3N4 three component electrocatalyst design concept for efficient and tunable CO2 reduction to syngas

“…5a), only hydrogen was detected in the gas phase and no reduction products from CO 2 reduction were observed. Pt is considered as the most efficient electrocatalyst to facilitate HER 36 . The application of Pt-CDots-C 3 N 4 as a catalyst shifts the balance between HER and CO 2 reduction toward H 2 generation, increases the intensity of the efficient HER channel and completely suppresses the CO 2 reduction to CO.…”

Perspective of Surfactant‐Free Colloidal Nanoparticles in Heterogeneous Catalysis

“…Thanks to the low required overpotential including favorable hydrogen adsorption and desorption properties (Sabatier principle), platinum has been used for decades as an active catalyst material for hydrogenation, photocatalytic water splitting, hydrogen evolution reaction and fuel cell‐related reactions like oxidation of hydrogen (HOR) and reduction of oxygen (ORR) . Due to high costs and limited resistance of platinum against Ostwald ripening, research endeavors often address alloy formation either in terms of nanoparticles free of expensive noble metals or containing only minute amounts of platinum . Here, the selective corrosion (leaching) of less noble metals is often used for synthesis, with less noble metal being dissolved from the surface leaving a nanoporous structure that is composed of the more noble and active metal (see PtCu, PtNi, CuAu, or AgAu).…”

2D and 3D Silica‐Template‐Derived MnO2 Electrocatalysts towards Enhanced Oxygen Evolution and Oxygen Reduction Activity

“…Development of low‐cost, efficient and environment friendly materials are more attractive for the commercialization of electrochemical energy conversion and storage devices . The design and development of bi‐functional electrocatalyst for oxygen electrode reactions (OER/ORR) are more desirable in regenerative fuel cell, metal/air batteries .…”