Ion trapping effect assisted in situ formation of dense amorphous-crystalline nanointerfaces on NiW alloy for boosting alkaline hydrogen evolution

A dense a-c nanointerfaces in situ formed on NiW alloy driven by K + insertion. • Nanointerfaces intervene in the hydrogen-bonded network to promote proton transfer. • Amorphous WO x facilitates K + intercalation by coupled ion-electron transfer. • WO x and K + -inserted WO x optimize *H adsorption and *OH desorption capacity of NiW alloy. • ( a-c )WO x /NiW delivers superior HER performance approaching that of 20% Pt/C. NiW alloys with unique corrosion resistance have garnered considerable attention for the alkaline hydrogen evolution reaction (HER). Incorporating amorphous WO x can overcome the performance limitations of ordered NiW alloys by exposing more active sites. However, the dissolution of tungsten oxides triggered by the K + ion trapping effect is inevitable yet often overlooked during alkaline HER. Herein, a K + ion trapping effect strategy is proposed for assisting in situ formation of dense amorphous-crystalline ( a-c ) nanointerfaces on NiW alloy ( a-c (WO x )/NiW), utilizing a WO 2.72 -encapsulated NiW alloy as a pre-catalyst, wherein the a-c nanointerfaces function as a regulator of interfacial water, a diffusion channel for ions, reactive species and electrons, and an activator of active sites. During HER, K + intercalation, proceeded by coupled ion-electron transfer (CIET), facilitates H 2 O access to the alloy, activates the Ni 3 hollow sites for additional *H adsorption, and modulates *OH desorption at the W sites. Simultaneously, the WO x component intervenes in the hydrogen-bond network to promote proton transfer and optimizes *H adsorption at the Ni 2 W 1 hollow sites of the alloy. Benefiting from the dense a-c nanointerfaces, a-c (WO x )/NiW delivers superior HER performance (58 ± 2 mV@50 mA cm −2 , Tafel slope 47 ± 2 mV dec −1 ), approaching that of commercial 20% Pt/C. This work reveals the evolution behavior of tungsten oxides on NiW alloy surface under the K + ion trapping effect and offers new insights into the design of durable HER electrocatalysts. K + ion trapping effect assisted in-situ formation of dense a-c nanointerfaces on NiW alloy, functioning as a regulator of interfacial water, a diffusion channel for ions and electrons, and an exciter of active site. Download: Download high-res image (209KB) Download: Download full-size image