High-Efficiency Electrochemical Nitrate Reduction to Ammonia on a Co₃O₄ Nanoarray Catalyst with Cobalt Vacancies

Abstract

Electrocatalytic nitrate reduction reaction (NO 3 RR) affords a bifunctional character in the carbon-free ammonia synthesis and remission of nitrate pollution in water. Here, we fabricated the Co 3 O 4 nanosheet array with cobalt vacancies on carbon cloth (v Co -Co 3 O 4 /CC) by in situ etching aluminum-doped Co 3 O 4 /CC, which exhibits an excellent Faradaic efficiency of 97.2% and a large NH 3 yield as high as 517.5 μmol h −1 cm −2 , better than the pristine Co 3 O 4 /CC. Theoretical calculative results imply that the cobalt vacancies can tune the local electronic environment around Co sites of Co 3 O 4 , increasing the charge and reducing the electron cloud density of Co sites, which is thus conducive to adsorption of NO 3 − on Co sites for greatly enhanced nitrate reduction. Furthermore, the v Co -Co 3 O 4 (311) facet presents excellent NO 3 RR activity with a low energy barrier of about 0.63 eV on a potentialdetermining step, which is much smaller than pristine Co 3 O 4 (1.3 eV).

Oxygen Vacancy Induced Strong Metal-Support Interactions on Ni/Ce0.8Zr0.2O2 Nanorod Catalysts for Promoting Steam Reforming of Toluene: Experimental and Computational Studies

“…The BET specific surface area of the irregular Ce 0.8 Zr 0.2 O 2 support (CZ-irg) was 24.9 m 2 /g, lower than that of the Ce 0.8 Zr 0.2 O 2 nanorod support. It suggested that the nanorod support could provide a larger specific area, which is beneficial to Ni dispersion and catalytic activity . After loading with Ni, both the BET surface area and total pore volume decreased.…”

Engineering CuOxNanoparticles on Cu Foam for Acidic Nitrate Reduction to Ammonium

“…Specifically, for instances, the CuO x /CuF catalyst with electrodeposition parameters of 400 s and −1.0 V attained a higher NH 4 + yield of ∼14 μmol h −1 cm −2 mM [NOd x ] at a lower potential of −0.5 V, as compared to FSP-CuO (∼6 μmol h −1 cm −2 mM [NOd x ] at −0.6 V), 15 Pd-TiO 2 (∼0. 42 Ru-ST-12 (∼1 μmol h −1 cm −2 mM [NOd x ] at −0.8 V), 43 Cu/Ni foam (∼5 μmol h −1 cm −2 mM [NOd x ] at −0.8 V), 20 and CF@Cu 2 O (∼7 μmol h −1 cm −2 mM [NOd x ] at −1.0 V). 22 mM [NOd x ] at −0.45 V) 18 and Cuboctahedron Pd/C (∼0.02 μmol h −1 cm −2 mM [NOd x ] at −0.2 V).…”

Ce-doped MoS2−xnanoflower arrays for electrocatalytic nitrate reduction to ammonia

“…Nevertheless, NO 3 RR activity is restricted by its complex eight-electron process and some side reactions including the HER, and thus efficient NO 3 RR catalysts are required to accelerate the NO 3 RR reaction kinetics while suppressing the side reactions. 17–30…”

“…Nevertheless, NO 3 RR activity is restricted by its complex eight-electron process and some side reactions including the HER, and thus efficient NO 3 RR catalysts are required to accelerate the NO 3 RR reaction kinetics while suppressing the side reactions. [17][18][19][20][21][22][23][24][25][26][27][28][29][30] MoS 2 has been extensively confirmed to be able to effectively electroreduce nitrogenous molecules into diverse value-added chemicals owing to the nitrogenase-analogous characteristic of Mo active sites, [31][32][33][34][35] as well as its other merits of a layered structure, natural abundance, ease of synthesis and high electrochemical stability. 36 Nevertheless, the investigations of MoS 2 -based electrocatalysts are quite limited for the NO 3 RR due possibly to their low electrical conductivity and poor intrinsic NO 3 RR activity.…”