Electrochemical nitrogen reduction (eNRR) requires sufficient N₂ activation without excessive H adsorption. To examine how this balance changes across related main-group oxide interfaces, Al₂O₃–rGO, Ga₂O₃–rGO and In₂O₃–rGO were prepared using the same procedure, with only the metal precursor changed.
The three composites showed clearly different adsorption behaviour. DFT calculations gave *N₂ and *H adsorption energies of −0.50 and −0.10 eV, respectively, for Al₂O₃–rGO, whereas Ga₂O₃–rGO bound H more strongly and In₂O₃–rGO interacted only weakly with both adsorbates. On Al₂O₃–rGO, 0.86 e was transferred to adsorbed N₂ and the N–N bond increased to 1.19 Å. Experimentally, Al₂O₃–rGO gave the highest eNRR performance, with an NH₃ yield rate of 46.9 ± 4.7 μg h⁻¹ mg⁻¹ and a Faradaic efficiency of 29.3 ± 1.8% at −0.40 V vs. RHE. Operando ATR-FTIR showed nitrogen-containing intermediates during electrolysis, and the calculated free-energy profile favored a distal pathway with a potential-determining step of 1.03 eV.
The Al-based interface was then used for preliminary modification with boron. Boron incorporation changed the electrochemical response of the composite and suggests that the Al–O–C environment can be further adjusted after the initial oxide–rGO interface has been formed. Although this part of the study is still being developed, the results so far support further investigation of compositionally modified Al₂O₃–rGO interfaces for eNRR.

electrocatalytic nitrogen reduction,interfacial coupling,carbon material,Main group chemistry