Three-Phase Heterojunction NiMo-Based Nano-Needle for Water Splitting at Industrial Alkaline Condition

Constructing heterojunction is an effective strategy to develop high-performance non-preciousmetal-based catalysts for electrochemical water splitting (WS). Herein, we design and prepare an N-doped-carbon-encapsulated Ni/MoO2 nano-needle with three-phase heterojunction (Ni/MoO2 @CN) for accelerating the WS under industrial alkaline condition. Density functional theory calculations reveal that the electrons are redistributed at the three-phase heterojunction interface, which optimizes the adsorption energy of H- and O-containing intermediates to obtain the best AG H . for hydrogen evolution reaction (HER) and decrease the AG value of rate-determining step for oxygen evolution reaction (OER), thus enhancing the HER/OER catalytic activity. Electrochemical results confirm that Ni/MoO2@CN exhibits good activity for HER (eta(-)(10)=33 mV, eta(-)(1000) =267 mV) and OER (eta(10) =250 mV, eta(1000) =420 mV). It shows a low potential of 1.86 V at 1000 mA cm(-2) for WS in 6.0 M KOH solution at 60 degrees C and can steadily operate for 330 h. This good HER/OER performance can be attributed to the three-phase heterojunction with high intrinsic activity and the self-supporting nano-needle with more active sites, faster mass diffusion, and bubbles release. This work provides a unique idea for designing high efficiency catalytic materials for WS.

Automated summary

Constructing heterojunctions is an effective strategy for developing high-performance catalysts for electrochemical water splitting. In this study, a N-doped carbon-encapsulated Ni/MoO2 nano-needle with three-phase heterojunction was designed and prepared. Theoretical calculations and electrochemical tests showed that the catalyst exhibited good activity for both hydrogen and oxygen evolution reactions, with stable performance for 330 hours. This was achieved through optimizing adsorption energy and increasing active sites.