Advances in Electrocatalysis for Energy Conversion and Synthesis of Organic Molecules

Abstract

Ubiquitous electrochemistry is expected to play a major role for reliable energy supply as well as for production of sustainable fuels and chemicals. The fundamental understanding of organics‐based electrocatalysis in alkaline media at the solid–liquid interface involves complex mechanisms and performance descriptors (from the electrolyte and reaction intermediates), which undermine the roads towards advance and breakthroughs. Here, we review and diagnose recently designed strategies for the electrochemical conversion of organics into electricity and/or higher‐value chemicals. To tune the mysterious workings of nanocatalysts in electrochemical devices, we examine the guiding principles by which the performance of a particular electrode material is governed, thus highlighting various tactics for the development of synthesis methods for nanomaterials with specific properties. We end by examining the production of chemicals by using electrochemical methods, from selective oxidation to reduction reactions. The intricate relationship between electrode and selectivity encourages both of the communities of electrocatalysis and organic synthesis to move forward together toward the renaissance of electrosynthesis methods.

Electrocatalytic and Electroanalytic Investigation of Carbohydrates Oxidation on Gold-Based Nanocatalysts in Alkaline and Neutral pHs

“…with the smallest overpotential); (iv) suppression of the formation of strongly adsorbed intermediate species. 12,25 We reported the use of "Bromide Anion Exchange" (BAE) method, [29][30][31] a surfactant-free approach, to develop a line-up of Au-Pd-Pt nanocatalysts able to oxidize efficiently glucose at low electrode potentials at various pHs. [32][33][34] It was also shown that monometallic Au enables a selective oxidation of a range of carbohydrates by their anomeric position and even in a cogeneration fuel cell; 13,35 however, it was postulated that the selectivity remained limited to Au that exhibits remarkable catalytic activity [36][37][38] toward aldehydes and hemiacetals oxidation.…”

“…New type of devices so-called "co-generation or co-production" FCs arise from the possibility of reaching efficiently and simultaneously these two goals. 8,9,[11][12][13][14][15] For instance, the current platforms for H 2 production are largely based on fossil fuels (steam methane reforming, coal gasification), and lead to the emission of significant quantities of greenhouse gases (CO 2 and other carbon-based species in addition to the need of high temperatures), which apparently violates our original intention of reducing global warming by the employment of H 2 power. 16 Besides, the organic electrosynthesis is expected to replace, somehow, toxic or hazardous reagents, avoid large quantities of stoichiometric oxidizers and reducers as well as the in situ production of unstable and/or hazardous chemicals, which means that the waste originating from the used reagents is almost negligible.…”

“…16 Besides, the organic electrosynthesis is expected to replace, somehow, toxic or hazardous reagents, avoid large quantities of stoichiometric oxidizers and reducers as well as the in situ production of unstable and/or hazardous chemicals, which means that the waste originating from the used reagents is almost negligible. 12,17,18 Therefore, seeking a clean, renewable and efficient strategy for electricity and fuels/chemicals production is needed.…”

“…Owing to their low oxidation potential compared to H 2 O, the efficiency of ECs can be much improved by oxidizing an organic compound at the anode in lieu of water molecules. 7,12 Indeed, a large cell voltage of ca. 2 V is needed to achieve a current density of ∼100 A dm −2 , which leads to a consumed electric energy of ∼5 kWh (Nm 3 H 2 ) −1 Refs.…”

“…At the same time, an alcohol instead of water as reactant for the oxidation reaction needs a voltage below 1 V and an electric energy lower than 3 kWh (Nm 3 H 2 ) −1 Refs. 7,12, that is roughly 50% energy saving. Up to now, the majority of electrolysis occurs in acidic media and needs precious and expensive metals (IrO 2 , RuO 2 , Pt), and only a few attempts have been dedicated to solid alkaline membrane electrolysis cells (SAMECs) for organics oxidation at the anode.…”