Modulation engineering of in situ cathodic activation of FeP based on W-incorporation for the hydrogen evolution reaction.

In situ electrochemical activation as a new pretreating method to adjust electrocatalytic performance attracts extensive attention. However, the activation mechanisms of electrocatalysts are still ambiguous. Herein, we propose a facile modulation strategy of in situ cathodic activation of FeP based on W-incorporation (W-FeP/IF) for the hydrogen evolution reaction (HER). The activated W-FeO with obvious surface reconstruction demonstrates the role of W-incorporation for driving the cathodic activation of FeP, which suggests the larger surface area and more active sites. In fact, W incorporation can not only accelerate the cathodic activation process but also act as the adsorption sites for H to form the synergistic effect with FeO for water dissociation. The obtained W-FeO/IF exhibits greatly enhanced HER activity featuring decreased overpotential from 237.7 to 154.0 mV at 100 mA cm, which may be ascribed to W-FeO with double catalytic active sites after cathodic activation. Additionally, the modulation effects of cathodic activation can be exactly achieved by changing electrochemical parameters such as CV cycles. W-FeO/IF also shows excellent long-term stability for at least 100 h at 100 mA cm. This modulation engineering based on metal doping is expected to provide inspiration for the understanding of the cathodic activation process for efficient electrocatalysts.