Nickel Iron Diselenide for Highly Efficient and Selective Electrocatalytic Conversion of Methanol to Formate

Abstract

The electro‐oxidation of methanol to formate is an interesting example of the potential use of renewable energies to add value to a biosourced chemical commodity. Additionally, methanol electro‐oxidation can replace the sluggish oxygen evolution reaction when coupled to hydrogen evolution or to the electroreduction of other biomass‐derived intermediates. But the cost‐effective realization of these reaction schemes requires the development of efficient and low‐cost electrocatalysts. Here, a noble metal‐free catalyst, Ni1−xFexSe2 nanorods, with a high potential for an efficient and selective methanol conversion to formate is demonstrated. At its optimum composition, Ni0.75Fe0.25Se2, this diselenide is able to produce 0.47 mmol cm−2 h−1 of formate at 50 mA cm−2 with a Faradaic conversion efficiency of 99%. Additionally, this noble‐metal‐free catalyst is able to continuously work for over 50 000 s with a minimal loss of efficiency, delivering initial current densities above 50 mA cm−2 and 2.2 A mg−1 in a 1.0 m KOH electrolyte with 1.0 m methanol at 1.5 V versus reversible hydrogen electrode. This work demonstrates the highly efficient and selective methanol‐to‐formate conversion on Ni‐based noble‐metal‐free catalysts, and more importantly it shows a very promising example to exploit the electrocatalytic conversion of biomass‐derived chemicals.

Alcohol oxidation with high efficiency and selectivity by nickel phosphide phases

“…To gain in-depth insights on the reaction mechanism, we conducted a set of experiments with the most active phase, Ni 12 P 5 . The literature describes the MOR mechanism as follows: 19,33 Surface Ni 2+ + OH À / Ni(OH) 2…”

“…To gain in-depth insights on the reaction mechanism, we conducted a set of experiments with the most active phase, Ni 12 P 5 . The literature describes the MOR mechanism as follows: 19,33 Surface Ni 2+ + OH − → Ni(OH) 2 Ni(OH) 2 + OH − ↔ NiOOH + H 2 O + e − , fastRCH 2 OH sol ↔ RCH 2 OH ads , rate limiting stepRCH 2 OH ads + NiOOH → RĊHOH ads + Ni(OH) 2 + e − + H + RĊHOH ads + H 2 O + 3NiOOH → RCOOH sol + 3Ni(OH) 2 …”

“…[12][13][14][15][16] Among the proposed materials to replace noble metals as catalysts for alcohol oxidation, transition metals, especially Ni, are a cheap alternative and produce valuable products such as aliphatic acids with very high selectivity. 10,[16][17][18][19] So far, faceted Ni nanoparticles, 20 Ni 3 C branched nanoparticles, 18 NiO, 21,22 Ni(OH) 2 , 23,24 doped NiO 25 and Ni(OH) 2 , 26 and Ni nitrides and selenides have been synthesized and tested, mainly for methanol oxidation. The accumulated body of knowledge points to a thin layer of oxidized Ni as the active material, usually Ni(OH) 2 , which is electrochemically oxidized to NiOOH and reduced back to Ni(OH) 2 as the alcohol (or water) is oxidized.…”

Unraveling the Mechanisms of Electrocatalytic Oxygenation and Dehydrogenation of Organic Molecules to Value‐Added Chemicals Over a Ni–Fe Oxide Catalyst

“…The efficient oxidation of methanol (MeOH) and ethanol (EtOH) as fuels in alkaline fuel cells could spur the commercialization of this type of device. [ 15–17 ] Besides, their selective electro‐oxidative transformation can produce valuable chemicals. The electrocatalytic oxidations of benzyl alcohol and benzylamine are of particular interest because they produce valuable chemicals: benzoic acid serves as a food preservative; N ‐benzylidenebenzylamine and nitriles are industrially relevant chemicals in the pharma and agro‐ and fine‐chemical industries.…”

In situ grown oxygen-vacancy-rich copper oxide nanosheets on a copper foam electrode afford the selective oxidation of alcohols to value-added chemicals

“…Currently, the industrial-scale production of formate/formic acid involves the combination of CO with methanol at 80 °C and 40 atm followed by the subsequent hydrolysis of the resulting methyl formate, which is an energy and cost-intensive process. This results in a fourfold higher price per metric ton of formate compared to methanol [8][9][10] . Similarly, acetic acid/ acetate is also a very important commodity chemical and finds a wide range of industrial applications 11 .…”