Advancing Pt-Based Catalysts for alkaline Hydrogen Evolution: Achieving Boron Doping using 2D Borophene
Authors: Park Minseon , Bae Sojin , Kim Won Bae , Seo Min Ho 
Published: December 2024

Platinum-based catalysts are widely utilized in various electrochemical reactions such as oxygen reduction, hydrogen evolution, and oxygen evolution reaction. However, the high cost of Pt necessitates research on alloys with various transition metals to enhance catalyst activity while reducing expenses. Unfortunately, conventional alloy catalysts often suffer from decreased stability as transition metal elements dissolve, leading to catalyst degradation [1]. Various modifications such as core-shell structures or ordered structures are being introduced to enhance durability. Despite the exceptional catalytic activity demonstrated by many newly developed catalysts, durability often remains a concern [2]. Prolonged operation can lead to nanoparticle agglomeration, resulting in reduced surface area and active sites.

In this study, boron is introduced to enhance durability by preventing particle agglomeration. Previous research has explored materials doped with boron or intermetallic structures as catalysts for various electrochemical reactions such as oxygen reduction, hydrogen evolution, and alcohol oxidation [3]. Boron has smaller electronegativity than metal elements and can expand the lattice of the metal via institutional doping. Consequently, the d-band center of the boron-introduced catalyst may downshift, weakening its bonding with oxygen or hydrogen and potentially improving activity.

Unlike many studies utilizing boric acid, sodium borohydride, diethylamine borane as boron sources, this study employs borophene, a 2D structure of boron sheet. Chemically synthesized hydrogenated borophene (HB) serves as both a reducing agent and a boron source, incorporating boron into Pt-based catalyst [4]. A combination of various physicochemical analyses and computational approaches is employed to investigate the structure of the borophene-assisted catalyst.

The introduction of boron in the form of borophene inhibits the nanoparticle agglomeration and particle size increase. Firstly, introducing borophene into Pt-metal alloy can suppress the unexpected growth of nanoparticle during constructing ordered structure. Intermetallic structure is usually formed through a few hours of heat treatment with high temperature. Typically, heat treatment leads to particle agglomeration, causing an increase in particle size. Compared with commercial Pt catalyst, Pt-metal alloy catalyst, and borophene-assisted Pt-metal catalyst, the introduction of boron in the form of borophene can reduce particle agglomeration during heat treatment. Additionally, the borophene-assisted Pt-based catalyst is employed in electrocatalytic reactions. Through durability tests lasting over 100 hours, borophene-assisted Pt-based catalyst exhibits superior durability in various electrochemical environments compared to conventional Pt catalysts and Pt-based catalyst without boron.

Borophene-assisted catalyst holds promise for convenient application in synthesizing various metal nanoparticles, playing a crucial role in preventing agglomeration and maintaining high performance over an extended period. This study will significantly contribute to research on catalysts with excellent durability.

This work has supported by the National Research Foundation of Korea (NRF) grant funded by the Ministry of Science and ICT in Republic of Korea (MSIT) (NRF-2022R1A2C2093090), Ministry of Trade, Industry & Energy (MOTIE, Korea) under the Technology Innovation Program (20019175) supervised by the Korea Evaluation Institute of Industrial Technology(KEIT), and “Digital manufacturing platform" (No. P0022331) supervised by the Korea Institute for Advancement of Technology (KIAT).

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