Laser-Induced HKUST-1 Derived Porous Electrocatalyst: an Innovative Approach to Boost Sustainable Ammonia Synthesis

Abstract

Conventional synthesis methods of metal-embedded graphene electrodes are time-consuming, energy-extensive, and complex multi-step fabrications, limiting the large-scale production of the materials. This study uses laser processing to fabricate HKUST-1 MOF (Cu₃(C₉H₃O₆)₂)-derived porous Cu-Cu₂O/C (L-HKUST-1) electrocatalyst under ambient conditions for the electrocatalytic nitrate reduction to ammonia (E-NRA). The swift, one-pot, binder-free, zero waste, and scalable laser processing technique enables directly printing Cu-Cu₂O nanoparticles embedded in a carbon matrix on the nickel substrate under ambient temperature and pressure. Chemical and morphological characterization corroborate the transformation of pristine HKUST-1 to L-HKUST-1, thereby validating that the laser parameters (power, scan rate, resolution) are optimum for the successful fabrication of L-HKUST-1. Electrochemical nitrate reduction is a sustainable way to produce ammonia and can potentially promote a carbon-neutral economy. The electrochemical investigation demonstrates that the maximum yield of ammonia and Faradaic efficiency for L-HKUST-1 are 13,871.58 ± 17.11 µg h⁻¹ mg ⁻¹_(cat) at −0.65 V versus RHE (Reversible Hydrogen Electrode) and 80 ± 6.7% at −0.45 V, respectively. Augmented positive overpotential at −10 mAcm⁻² in the presence of the nitrate source confirms the superior electrocatalytic behavior for E-NRA.