Highly efficient electrocatalytic hydrogen evolution coupled with upcycling of microplastics in seawater enabled via Ni3N/W5N4 janus nanostructures

Electrochemical hydrogen evolution reaction (HER) coupled with microplastics reforming are critical for marine energy and environmental engineering, but filled with challenges. Herein, Ni 3 N/W 5 N 4 Janus nanostructure with barrier-free heterointerface was designed via transition metal nitrides-inducing growth strategy. Benefiting from the interface synergistic effect, super-hydrophilic surface and multilevel Janus structure, Ni 3 N/W 5 N 4 electrode displays Pt-like HER performance and the outstanding stability (~300 h) under industrially current. Meanwhile, Ni 3 N/W 5 N 4 also exhibits high activity and selectivity toward electro-reforming of plastics, showing an ultralow overpotential of 1.33 V (η 10 ) and generating the value-added HCOOH with the high Faradic efficiency of ~85%. Impressively, driven by solar panels, the bifunctional Ni 3 N/W 5 N 4 electrocatalyst achieves the highly efficient production of H 2 and HCOOH (η 10 =1.4 V, η solar to hydrogen =16.04%) in seawater full of plastics. This work underlines the on-site upgrading of plastic wastes and energy-saving hydrogen evolution in seawater enabled by the design of Janus heterostructures for metal nitrides. Ni 3 N/W 5 N 4 Janus nanostructure was designed via transition metal nitrides-inducing growth strategy for efficient electro-upgrading of plastics and HER in seawater. • Ni 3 N/W 5 N 4 Janus nanostructure was designed via transition metal nitrides-inducing growth strategy. • Synergistic effect, super-hydrophilic surface and confinement effect exist in Janus interface. • Ni 3 N/W 5 N 4 electrode displays Pt-like HER performance and the outstanding stability. • Ni 3 N/W 5 N 4 also exhibits high activity and selectivity toward electro-reforming of plastics. • The on-site upgrading of plastic wastes and energy-saving hydrogen evolution were realized.