Rational fabrication of Ni2P-Ni12P5 heterostructure with built-in electric-field effects for high-performance urea oxidation reaction.

[Display omitted] • Heterostructure Ni 2 P/Ni 12 P 5 is rationally fabricated via a facile solution combustion route. • Heterostructure and defective substrate benefit the optimized electric field and electron transfer. • The optimal catalyst exhibits a low potential of 1.32 V@100 mA cm−2 and a Tafel slope of 31.4 mV dec−1 in UOR. • The heterostructure enhances the adsorption of the reaction intermediate by redistributing the interfacial charge. Developing efficient electrocatalysts and investigating catalytic mechanisms are crucial in urea oxidation reaction (UOR) as a promising strategy to boost the energy efficiency of hybrid water electrolysis for H 2 production. The present work rationally designed and fabricated Ni 2 P-Ni 12 P 5 heterostructure with varying relative ratios embedded on the defective carbon–nitrogen-phosphorus substrate (Ni 2 P-Ni 12 P 5 /CNP) for high-performance UOR in alkaline conditions through a facile solution-combustion route without extra phosphorus sources. The developed synthesis method avoids the high cost, complicated routes, and extremely toxic emissions. Experimental and theoretical studies demonstrated that the Ni 2 P-Ni 12 P 5 heterostructure regulated the interfacial electric field and promoted electron transfer. The abundantly defective CNP substrate improved the electrical conductivity and prevented Ni 2 P-Ni 12 P 5 heterostructure from corrosion and detachment. The optimal electrocatalyst, with an approximately equal content of Ni 2 P and Ni 12 P 5 , exhibits a low potential of 1.32 V to deliver 100 mA cm−2, a small Tafel slope of 31.4 mV dec−1, robust stability of 80 h in UOR, and a low voltage of 1.85 V to reach 100 mA cm−2 in HER||UOR. This work provides a facile route to design electrocatalysts for efficient electrochemical hydrogen production. [ABSTRACT FROM AUTHOR]