RESUMO
The design and fabrication of high-performance, inexpensive and durable electrocatalyst toward hydrogen evolution reaction (HER) is supremely significant for alleviating energy crisis and environmental concerns, but still remaining challenging. Herein, we develop an experimental work based on etching and reduction strategy to reveal the remarkable effect of cation/anion co-doping in CoMoO4 on its intrinsic HER activity. The CoMoO4 with Fe and B incorporation (Fe/B-CoMoO4) exhibits a current density of 10 mA cm-2 with strikingly low potential of 38 mV coupling with Tafel slope of 51 mV dec-1, and manifesting a robust durability for 100 h with no attenuation, which is comparable to the state-of-the-art commercial Pt/C catalyst. The collective experimental and theoretical findings concomitantly illustrate that the enhanced performances are due to the strong synergistic effect resulting from the co-doping of Fe and B, which plays a pivotal role in finely tuning the electronic structure of CoMoO4, further optimizing the adsorption free energy of H intermediates and shifting the center of the d-band of Fe/B-CoMoO4 away from the Fermi level. This fantastic work highlights the critical role of foreign element incorporating for optimizing electronic structure of transition metal oxides toward HER, and offers valuable guiding principles for rational design of more efficient energy conversion devices.
RESUMO
Defect engineering is considered as a flexible and effective mean to improve the performance of Fenton-like reactions. Herein, a simple method is employed to synthesize Co3O4 catalysts with Co-O vacancy pairs (VP) for peroxymonosulfate (PMS) activation. Multi-scaled characterization, experimental, and simulation results jointly revealed that the cation vacancies-VCo contributed to enhanced conductivity and anion vacancies-VO provided a new active center for the 1O2 generation. Co3O4-VP can optimize the O 2p and Co 3d bands with the strong assistance of synergistic double vacancies to reduce the reaction energy barrier of the "PMS â Co(IV) = O â 1O2" pathway, ultimately triggering the stable transition of mechanism. Co3O4-VP catalysts with radical-nonradical collaborative mechanism achieve the synchronous improvement of activity and stability, and have good environmental robustness to favor water decontamination applications. This result highlights the possibility of utilizing anion and cation vacancy engineering strategies to rational design Co3O4-based materials widely used in catalytic reactions.
RESUMO
Developing highly active and durable non-precious metal-based electrocatalysts for the oxygen evolution reaction (OER) is crucial in achieving efficient energy conversion. Herein, we reported a CoNiAl0.5O/NF nanofilament that exhibits higher OER activity than previously reported IrO2-based catalysts in alkaline solution. The as-synthesized CoNiAl0.5O/NF catalyst demonstrates a low overpotential of 230 mV at a current density of 100 mA cm-2, indicating its high catalytic efficiency. Furthermore, the catalyst exhibits a Tafel slope of 26 mV dec-1, suggesting favorable reaction kinetics. The CoNiAl0.5O/NF catalyst exhibits impressive stability, ensuring its potential for practical applications. Detailed characterizations reveal that the enhanced activity of CoNiAl0.5O/NF can be attributed to the electronic modulation achieved through Al3+ incorporation, which promotes the emergence of higher-valence Ni metal, facilitating nanofilament formation and improving mass transport and charge transfer processes. The synergistic effect between nanofilaments and porous nickel foam (NF) substrate significantly enhances the electrical conductivity of this catalyst material. This study highlights the significance of electronic structures for improving the activity of cost-effective and non-precious metal-based electrocatalysts for the OER.