Nanostructured LaNiO₃ Perovskite Electrocatalyst for Enhanced Urea Oxidation

Abstract

Urea electrooxidation has attracted considerable interest as an alternative anodic reaction in the electrochemical generation of hydrogen due to both the lower electrochemical potential required to drive the reaction and also the possibility of eliminating a potentially harmful substance from wastewater during hydrogen fuel production. Nickel and nickel-containing oxides have shown activities comparable to those of precious-metal catalysts for the electrooxidation of urea in alkaline conditions. Herein, we investigate the use of nanostructured LaNiO3 perovskite supported on Vulcan carbon XC-72 as an electrocatalyst. This catalyst exhibits an exceptionally high mass activity of ca. 371 mA mgox –1 and specific activity of 2.25 A mg–1 cmox –2 for the electrooxidation of urea in 1 M KOH, demonstrating the potential applications of Ni-based perovskites for direct urea fuel cells and low-energy hydrogen production. While LaNiO3 is shown to be stable at low overpotentials, through in-depth mechanistic studies the catalyst surface was observed to restructure and there was apparent CO2 poisoning of the LaNiO3 upon extended cycling, a result that may be extended to other Ni-based systems.

Exceptional electrocatalytic oxygen evolution via tunable charge transfer interactions in La0.5Sr1.5Ni1−xFexO4±δ Ruddlesden-Popper oxides

“…4a. The potential range over which the redox peaks are observed is consistent with prior studies of Ni-based electrocatalysts 3,35,36 with Fe substitution shifting the peak potential ( E P ) of Ni 2+/3+ oxidation as documented with Ni–Fe oxyhydroxides 3,4,35 . Integration of the oxidation waves (Supplementary Figures 15 and 16) reveals that the specific oxidative charge (µC cm −2 oxide ) transferred during oxidation/intercalation consistently decreases upon continued replacement of Ni with Fe, with the exception of the initial introduction of Fe in LSNF15 (Fig.…”

An Insight on the Electrocatalytic Mechanistic Study of Pristine Ni MOF (BTC) in Alkaline Medium for Enhanced OER and UOR

“…[15,20] Methanol, ammonia and urea offer an easy way to store hydrogen as a low cost chemical in industrial scale as well as urea is found in fertilizers and municipal waste water from human/animal urine. [22][23][24][25]28] Similar to OER in WE, Ni based catalysts such as nano sized nickel, LaNiO 3 , NiÀFe double hydroxide, Ni 2 P, Ni(OH) 2 , Ni nanoparticles decorated NiFe double hydroxide, Ni x Mn y O 4 show catalytic activity towards UOR. [23][24][25][26][27] Because of its lower energy consumption, wider availability, renewability, non-flammability and non-toxic nature, UE enables H 2 production from the urea rich waste water and animals excreta.…”

“…[19][20][21] Ni based materials in different forms including oxide, sulfide, phosphide, nitride are explored towards OER, which show h of 300 to 500 mV at a current density of 10 mA cm À2 in alkaline medium and vary depending upon the synthesis conditions, chemical composition, electrolyte concentration, measuring conditions (dynamic or steady state or hydrodynamic) and choice of substrate under identical conditions. [23][24][25][26][27] Because of its lower energy consumption, wider availability, renewability, non-flammability and non-toxic nature, UE enables H 2 production from the urea rich waste water and animals excreta. [22] Splitting of hydrogen (H 2 ) from urea through urea electrolysis (UE) is closer to WE as urea oxidation reaction (UOR) occurs at 0.37 V vs. RHE (below 1.23 V vs. RHE), which lead to considerable interest in the energy sector for the production of H 2 .…”

Hollow Sodium Nickel Fluoride Nanocubes Deposited MWCNT as An Efficient Electrocatalyst for Urea Oxidation

“…Also storage of the fuel materials and safety are another concerns for this type of fuel cell. Direct urea/air fuel cell is free from these types of issues and still has the potential to achieve the optimum performance until and unless the search for a better catalyst for urea oxidation and other materials like cathodes and AEMs is exhausted [36][37][38].…”

“…Recent report on LaNiO3 for urea oxidation [36] stated that the synthesis of materials with inherent Ni 3+ oxidation state can lead to an efficient electrocatalytic activity towards urea oxidation. However, materials with inherent Ni 3+ have rarely been investigated till now for urea oxidation.…”