High-valence chromium accelerated interface electron transfer for water oxidation

Kong, Shaoxi; Lu, Mengfei; Yan, Shicheng; Zou, Zhigang

doi:10.1039/d2dt02908a

Cited by 5 publications

(1 citation statement)

References 45 publications

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“…As a cocatalyst, Cr synergistically improves the electrocatalytic activity . It is worth noting that relevant studies have shown that the presence of high-valence Cr enables a stronger interaction with the carbon matrix, reducing the adsorption free energy of OER intermediates at the active site and thus enhancing the OER activity. − However, high-valence Cr-based catalysts are usually difficult to obtain due to the requirement of high-temperature reactions and the use of oxidants. Therefore, we designed controlled pyrolysis to prepare chromium-oxide-based nanomaterials with a high oxidation state, expecting superior OER performance.…”

Section: Introductionmentioning

confidence: 99%

A Comprehensive Pyrolysis Mechanism of Binuclear Chromium-Based Complexes for Superior OER Activity

Gan,

Li,

Yang

et al. 2024

ACS Appl. Mater. Interfaces

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Transition metal oxides are widely pursued as potent electrocatalysts for the oxygen evolution reaction (OER). However, single-metal chromium catalysts remain underexplored due to their intrinsic activity limitations. Herein, we successfully synthesize mixed-valence, nitrogen-doped Cr 2 O 3 /CrO 3 /CrN@NC nanoelectrocatalysts via one-step targeted pyrolysis techniques from a binuclear Cr-based complex (Cr 2 (Salophen) 2 (CH 3 OH) 2 ), which is strategically designed as a precursor. Comprehensive pyrolysis mechanisms were thoroughly delineated by using coupled thermogravimetric analysis and mass spectrometry (TG−MS) alongside X-ray diffraction. Below 800 °C, the generation of a reducing atmosphere was noted, while continuous pyrolysis at temperatures exceeding 800 °C promoted highly oxidized CrO 3 species with an elevated +6 oxidation state. The optimized catalyst pyrolyzed at 1000 °C (Cr 2 O 3 /CrO 3 /CrN@NCs-1000) demonstrated remarkable OER activity with a low overpotential of 290 mV in 1 M KOH and excellent stability. Further density functional theory (DFT) calculations revealed a much smaller reaction energy barrier of CrO 3 than the low oxidation state species for OER reactivity. This work reveals fresh strategies for rationally engineering chromium-based electrocatalysts and overcoming intrinsic roadblocks to enable efficient OER catalysis through a deliberate oxidation state and compositional tuning.

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