Elucidating the formation and structural evolution of platinum single-site catalysts for hydrogen evolution reaction

Abstract

Platinum single-site catalysts (SSCs) are a promising technology for the production of hydrogen from clean energy sources. They have high activity and maximal platinum-atom utilisation. However, the bonding environment of platinum during operation is poorly understood. In this work, we use operando, synchrotron-X-ray absorption spectroscopy to study the platinum bonding in SSCs. First, we synthesise an atomically dispersed platinum complex with aniline and chloride ligands onto graphene and characterise it with ex-situ electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, X-ray absorption near edge structure spectroscopy (XANES), and extended X-ray absorption fine structure spectroscopy (EXAFS). Then, by operando EXAFS and XANES, we show that as a negatively biased potential is applied, the Pt-N bonds break first followed by the Pt-Cl bonds. The platinum is reduced from platinum(II) to metallic platinum(0) by the onset of the hydrogen-evolution reaction at 0 V. Furthermore, we observe an increase in Pt-Pt bonding, indicating the formation of platinum agglomerates. Together, these results indicate that while aniline is used to prepare platinum SSCs, the single-site complexes are decomposed and platinum agglomerates at operating potentials. This work is an important contribution to the understanding of the bonding environment and the evolution of the molecular structure of platinum complexes in SSCs.

Platinum-Anchored Iron Oxide Nanostructures for Efficient Hydrogen Evolution Reaction in Acidic Media

“…40 However, with an increase in the Pt loading, an additional peak appeared at 1.89 Å with Pt 2 /Fe 2 O 3 and became the dominant feature in Pt 5 /Fe 2 O 3 and Pt 10 /Fe 2 O 3 , which most likely arose from the Pt−Cl path. 41 This is in good agreement with results from XPS measurements where the contents of Cl residuals increased from Pt 0.5 /Fe 2 O 3 to Pt 10 / Fe 2 O 3 and the Cl residuals were mostly bonded to Pt (Table S2). Such a dynamic evolution of the atomic configurations can also be manifested in the corresponding wavelet transforms (WT) using commercial Fe 2 O 3 and PtO 2 as the references (Figure S15).…”

Atomically Dispersed Fe–N5 Sites Anchored in Porous N-Doped Carbon Nanofibers for Effective Hydrogen Evolution Reaction

“…According to Figure 2a, the oxidation state of Fe in Fe SA/PCNFs-0.1 increases relative to FePc, the absorption peak shifts to the high energy region, and the intensity of the white line peak increases, demonstrating that the valence state of Fe is higher than that in FePc. 29,30 The oxidation state of Fe species in Fe SA/PCNFs-0.1 is +a (2 < a < 3). 31 The coordination between Fe and N would induce nearby N atoms to consume Fe free electrons through valence bonding.…”

Reactive template‐derived interfacial engineering of CoP/CoO heterostructured porous nanotubes towards superior electrocatalytic hydrogen evolution

“…To date, noble metal Pt is still recognized as the state-ofthe-art HER catalyst, but its exorbitant cost, scarce reserves, and inferior durability severely restrict its widespread industrial deployment. [11][12][13] In this context, it is of great importance to develop inexpensive and active alternatives with Pt-like performance to achieve sustainable hydrogen production economically viable.…”

“…Nevertheless, currently, the implementation of electrochemical water splitting technology heavily relies on the usage of efficient, durable, and affordable electrocatalysts. To date, noble metal Pt is still recognized as the state‐of‐the‐art HER catalyst, but its exorbitant cost, scarce reserves, and inferior durability severely restrict its widespread industrial deployment 11–13 . In this context, it is of great importance to develop inexpensive and active alternatives with Pt‐like performance to achieve sustainable hydrogen production economically viable.…”