Selective Electrooxidation of Biomass‐Derived Alcohols to Aldehydes in a Neutral Medium: Promoted Water Dissociation over a Nickel‐Oxide‐Supported Ruthenium Single‐Atom Catalyst

Abstract

The biomass‐derived alcohol oxidation reaction (BDAOR) holds great promise for sustainable production of chemicals. However, selective electrooxidation of alcohols to value‐added aldehyde compounds is still challenging. Herein, we report the electrocatalytic BDAORs to selectively produce aldehydes using single‐atom ruthenium on nickel oxide (Ru1‐NiO) as a catalyst in the neutral medium. For electrooxidation of 5‐hydroxymethylfurfural (HMF), Ru1‐NiO exhibits a low potential of 1.283 V at 10 mA cm−2, and an optimal 2,5‐diformylfuran (DFF) selectivity of 90 %. Experimental studies reveal that the neutral electrolyte plays a critical role in achieving a high aldehyde selectivity, and the single‐atom Ru boosts HMF oxidation in the neutral medium by promoting water dissociation to afford OH*. Furthermore, Ru1‐NiO can be extended to selective electrooxidation of a series of biomass‐derived alcohols to corresponding aldehydes, which are conventionally difficult to obtain in the alkaline medium.

Spinel-Derived Formation and Amorphization of Bimetallic Oxyhydroxides for Efficient Electrocatalytic Biomass Oxidation

“…64 Overall, it can be concluded in panels a and b of Figure 3 that for spinel oxide and sulfide with same cation composition, the spinel sulfides typically showed further improved BEOR performance (e.g., Co 3 S 4 vs Co 3 O 4 and CuCo 2 S 4 vs CuCo 2 O 4 ) due to amorphization and oxygen defects to boost the oxygencontaining species adsorption; the one exception was that NiCo 2 S 4 and NiCo 2 O 4 showed similar activities. This unique behavior is consistent with the fact that Ni atoms can serve as added active sites (in addition to Co) for OER, 14,[51][52][53][54][55][56]65 which apparently reduces the overall FE for BEOR in the NiCoOOH catalyst.…”

“…With a decreased KOH concentration (0.1 M KOH with 50 mM Fu/HMF), 87% FCA and 28% FDCA production were also obtained from the CuCo 2 S 4 electrode, indicating a sufficient capability of CuCo 2 S 4 for biomass electrooxidation under less alkaline conditions. 33,34 Overall, the electrocatalytic Fu/HMF oxidation performance using spinelbased catalysts decreases in the following order:…”

Electroreforming injects a new life into solid waste

“…251 In this context, a neutral medium seems to be a better choice for the realization of HMF-to-DFF conversion, as evidenced by Wang's report, 250 where the oxidation of the aldehyde group of HMF was significantly suppressed in a neutral electrolyte. Encouraged by this finding, Duan et al 252 constructed single-atom Ru supported on NiO (Ru/NiO) to selectively steer the conversion of HMF into DFF under neutral conditions, with a selectivity of up to 90%. The experimental observation combined with theoretical calculations collectively revealed that the neutral conditions played a vital role in DFF production and single-atom Ru promoted the HMF oxidation via accelerating water dissociation for OH* evolution.…”

A mini review of electrocatalytic upgrading of carbohydrate biomass—System, path, and optimization

“…Both DFF and HMFCA are further oxidized to form 2-formyl-2furancarboxylic acid, which is then ultimately oxidized to form FDCA. 48,49 Moreover, under acidic conditions (e.g., 1.0 mol L −1 H 2 SO 4 solution) and with a high applied potential, HMF can also generate maleic acid (MA) as a product. But the formation of MA is undesirable because it consumes HMF and reduces the yield of FDCA.…”

“…On the other hand, under strong alkaline conditions (e.g., 1.0 mol L − 1 KOH solution), HMF is oxidized to 5‐hydroxymethyl‐2‐furancarboxylic acid (HMFCA) as the first intermediate. Both DFF and HMFCA are further oxidized to form 2‐formyl‐2‐furancarboxylic acid, which is then ultimately oxidized to form FDCA 48,49 . Moreover, under acidic conditions (e.g., 1.0 mol L − 1 H 2 SO 4 solution) and with a high applied potential, HMF can also generate maleic acid (MA) as a product.…”