Self-supported CoNiFe@Mo–Ni3S2 heterophase electrocatalyst for direct coal gasification wastewater electrolysis

Development of robust and corrosion-resistant anodes is crucial for large-scale alkaline industrial coal gasification wastewater (CGW) electrolysis in an anion-exchange membrane water electrolyser (AEMWE). Herein, we develop a corrosion strategy to construct a self-supported electrocatalyst (CoNiFe@Mo–Ni 3 S 2 ) with high mechanical stability by anchoring the CoNiFe medium-entropy alloy catalytic layer onto a dense interlayer of Mo–Ni 3 S 2 support. The CoNiFe@Mo–Ni 3 S 2 catalyst exhibits a strengthened heterophase between the crystalline Mo–Ni 3 S 2 interlayer and amorphous CoNiFe catalytic layer, significantly facilitating electron diffusion and reaction kinetics. In 1 M KOH +50% CGW, the CoNiFe@Mo–Ni 3 S 2 electrode delivers low apparent anodic overpotentials of 124 and 202 mV at 50 and 100 mA cm −2 , respectively, where OER is coupled with the electrooxidation of ammonia nitrogen and organic pollutants. The CoNiFe@Mo–Ni 3 S 2 -based AEMWE single cell further achieves a current density of 0.5 A cm −2 at 1.74 V. Remarkably, the system simultaneously achieves 92.6% ammonia-nitrogen removal and 51.4% chemical oxygen demand (COD) reduction. Post-reaction Raman, XRD, and XPS analyses reveal that interfacial electronic coupling between crystalline Mo–Ni 3 S 2 and amorphous CoNiFe promotes surface reconstruction into high-valence (Ni, Co, Fe)–OOH species, while the residual sulfide interlayer provides conductive and mechanically robust support. These results demonstrate the potential of CoNiFe@Mo–Ni 3 S 2 for coupling hydrogen production with CGW treatment and resource utilization.