Hanxiao Liao,Tao Luo,Pengfei Tan,Kejun Chen,Lili Lu,Yong Liu,Min Liu,Jun Pan
The rational design of effective catalysts for sluggish oxygen evolution reactions (OERs) is desired but challenging. Nickel-iron (NiFe) (oxy)hydroxides are promising pre-electrocatalysts for alkaline OER. However, OER performances are limited by the slow reconstruction process to generate active species of high-valance NiFe oxyhydroxides. In this work, a sulfate ion (SO 4 2− ) modulated strategy is developed to boost the OER activity of NiFe (oxy)hydroxide by accelerating the electrochemical reconstruction of pre-catalyst and stabilizing the reaction intermediate of OOH* during OER. The SO 4 2− decorated NiFe (oxy)hydroxide catalyst (NF-S0.15) is fabricated via scalable anodization of NiFe foam in a thiourea-dissolved electrolyte. The experimental and theoretical investigations demonstrate the dual effect of SO 4 2− on improving OER performances. SO 4 2− leaching is favorable for the electrochemical reconstruction to form active NiFeOOH under OER condition. Simultaneously, the residual SO 4 2− adsorbed on surface can stabilize the intermediate of OOH*, and thus enhance the OER performances. As expected, NF-S0.15 delivers an ultralow overpotential of 234 mV to reach the current density of 50 mA cm −2 , a fast OER kinetics (27.7 mV dec −1 ), and a high stability for more than 100 h. This unique insights into anionic modification could inspire the development of advanced electrocatalysts for efficient OER.
Ruoxuan Sun,Minghui Zhu,Jie Chen,Lei Yan,Liyi Bai,Jiqiang Ning,Yijun Zhong,Yong Hu
The electrochemical synthesis of hydrogen peroxide (H2O2) via the two-electron oxygen reduction reaction (2e– ORR) is a promising alternative to the conventional anthraquinone method. However, due to local alkalinization near the catalyst surface, the restricted oxygen replenishment and insufficient activated water molecule supply limit the formation of the key *OOH intermediate. Herein, a pulsed electrocatalysis approach based on a structurally optimized S/N/O tridoped hollow carbon bowl catalyst has been proposed to overcome this challenge. In an H-type electrolytic cell, the pulsed method achieves a superior H2O2 yield rate of 55.6 mg h–1 mgcat.–1, approximately 1.6 times higher than the conventional potentiostatic method (34.2 mg h–1 mgcat.–1), while maintaining the Faradaic efficiency above 94.6%. In situ characterizations, finite element simulations, and density functional theory analyses unveil that the application of pulsed potentials mitigates the local OH– concentration, enhances the water activation and proton generation, and facilitates oxygen production within the hollow bowl-like carbon structure. These effects synergistically accelerate the formation kinetics of the *OOH intermediate by the efficient generation of *O2 and *H2O intermediates, leading to superior H2O2 yields. This work develops a strategy to tune catalytic environments for diverse catalytic applications.
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