Insights into the activity of nickel boride/nickel heterostructures for efficient methanol electrooxidation

Abstract

Designing efficient catalysts and understanding the underlying mechanisms for anodic nucleophile electrooxidation are central to the advancement of electrochemically-driven technologies. Here, a heterostructure of nickel boride/nickel catalyst is developed to enable methanol electrooxidation into formate with a Faradaic efficiency of nearly 100%. Operando electrochemical impedance spectroscopy and in situ Raman spectroscopy are applied to understand the influence of methanol concentration in the methanol oxidation reaction. High concentrations of methanol inhibit the phase transition of the electrocatalyst to high-valent electro-oxidation products, and electrophilic oxygen species (O* or OH*) formed on the electrocatalyst are considered to be the catalytically active species. Additional mechanistic investigation with density functional theory calculations reveals that the potential-determining step, the formation of *CH2O, occurs most favorably on the nickel boride/nickel heterostructure rather than on nickel boride and nickel. These results are highly instructive for the study of other nucleophile-based approaches to electrooxidation reactions and organic electrosynthesis.

Methanol upgrading coupled with hydrogen product at large current density promoted by strong interfacial interactions

“…When the potential increased, the adsorbed CH 3 OH was converted to formate through deprotonation, electron transfer, and hydroxyl addition. 51 It is worth noting that the dehydrogenation step of Fe 2 O 3 where the O-H chemical bond is broken, requires relatively higher energy barriers (2.37 eV) than those needed in the subsequent steps, which…”

Redox mediators promote electrochemical oxidation of nitric oxide toward ambient nitrate synthesis

“…S20†) only show approximated steep lines at the potentials of 1.07 V RHE and 1.12 V RHE due to high charge-transfer resistances for water oxidation, while a semicircle begins to take shape when the potential increases to 1.27 V SCE , thus suggesting the occurrence of the OER. 55–58 Moreover, the Bode phase plots of Co 3 O 4 /Ti after long-term electrolysis at high j (Fig. 4e) still show the high frequency (∼10 3 Hz) peak.…”

“…Except for the peak at a frequency of ∼10 3 Hz that corresponds to the Co–O 6 Oh active site in the Bode plots, another peak at a frequency of 10 −0.5 Hz appears simultaneously at only 0.47 V SCE and shifts to the higher frequency (near 10 0.5 Hz) with the increase in nitrite concentration, indicating the change of the catalytic reaction interface from the low-frequency interface to the middle-frequency interface. 57 Based on the above results (quasi- in situ XPS, in situ Raman, and in situ EIS analysis), we deduced that, even at high electrode potentials, oxidation of low-valence Co can be well-prevented in the presence of Cl − (higher adsorbed chlorine species coverage) in the acidic solution, and the favoured catalytic ability of our Co 3 O 4 /Ti for the eCOR-NOOR should be essentially dominated by Co 2+ Td sites.…”

Porous Nanoarchitectures of Nonprecious Metal Borides: From Controlled Synthesis to Heterogeneous Catalyst Applications

“…To regulate the properties of Earth-abundant metals, combining the metals with second or third elements as well as meeting various application requirements is another imperative strategy. Many studies have proven that alloying the Earth-abundant metals with nonmetal/metalloid elements, such as S, N, B, and P, is an effective strategy for tuning their physicochemical properties and the local atomic structures of active sites, leading to improved performance in several applications. For example, B is located at the apex of the line separating metals and nonmetals in the Periodic Table, providing B with unique metalloid properties, which make it highly versatile in chemical reactions and applications.…”