CoFe-based catalysts have shown excellent activity for the oxygen evolution reaction (OER), with the oxidation states of the active sites playing a crucial role in determining catalytic performance. However, how to effectively increase the oxidation state of these active sites remains a key challenge. In this work, a facile treatment with NaBH4solution was employed to modulate the surface state of CoFeOxHycatalysts, inducing an enhanced OER activity. The overpotential at 10 mA cm−2for the NaBH4-treated CoFe catalyst was reduced to 270 mV, indicating improved OER activity. X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) results reveal that NaBH4treatment induced a phase reconstruction of the CoFe oxalate framework, a critical step in enhancing its catalytic properties. The strong reducing ability of NaBH4strengthened the Co-Fe interaction, allowing the retention of low-valence Co species while facilitating the formation of high-valence Fe sites. This dual modulation of Co and Fe oxidation states significantly accelerated charge transfer kinetics, ultimately boosting OER performance. These findings highlight the importance of improving the oxidation states of active sites in CoFe-based catalysts, providing insights for developing efficient catalysts for electrochemical water splitting.
The construction of high-performance sensitive materials is a basis for excellent sensors. Among prior SnS 2 -based sensors, high sensing performance often accompanies high operating temperatures or expensive costs, which limits their practical use. Herein, we employed Sr doping and NaBH 4 treatment strategies to increase the S-vacancies content in the SnS 2 microflowers. Particularly, this composite sensitive material shows large specific surface area, low crystallinity and rich S-vacancies content, which enables this sensor excellent sensing properties toward NO 2 , with a response of 4.7 toward 5 ppm NO 2 at 100 °C. In addition, this sensor has a low detection limit for NO 2 as low as 0.2 ppm, which is a lower value compared to many SnS 2 -based NO 2 sensors as reported. XRD, SEM, TEM, EPR and BET characterization combined with density functional theory (DFT) calculations are adopted to illustrate the enhancement mechanism toward NO 2 of the composite sensitive materials fabricated in this work. This study provides new ideas and scientific basis for the construction of metal sulfide based NO 2 sensors, which has important theoretical significance and application value.
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