Removing excess nitrate (NO3 –) from waste streams has become a significant environmental and health topic. However, realizing highly selective NO3 – conversion toward N2, primarily via electrocatalytic conversions, has proven challenging, largely because of the kinetically uncontrollable NO3 –-to-NO2 – pathway and unfavorable N–N coupling. Herein, we discovered unique and ultra-high electrocatalytic NO3 –-to-NO2 –activity on oxide-derived silver (OD-Ag). Up to 98% selectivity and 95% Faradaic efficiency (FE) of NO2 – were observed and maintained under a wide potential window. Benefiting from the superior NO3 –-to-NO2 –activity, further reduction of accumulated NO2 – to NH4 + was well regulated by the cathodic potential and achieved an NH4 + FE of 89%, indicating a tunable selectivity to the key nitrate reduction products (NO2 – or NH4 +) on OD-Ag. Density functional theory computations provided insights into the unique NO2 – selectivity on Ag electrodes compared with Cu, showing the critical role of a proton-assisted mechanism. Based on the ultra-high NO3 –-to-NO2 – activity on OD-Ag, we designed a novel electrocatalytic–catalytic combined process for denitrifying real-world NO3 –-containing agricultural wastewater, leading to 95+% of NO3 – conversion to N2 with minimal NOX gases. In addition to the wastewater treatment process to N2 and the electrochemical synthesis of NH3, NO2 – derived from electrocatalytic NO3 – conversion can serve as a reactive platform for the distributed production of various nitrogen products.

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Electrocatalytic upgrading of biomass-derived feedstocks driven by renewable electricity offers a greener way to reduce the global carbon footprint associated with the production of value-added chemicals. In this respect, a...

Water electrolysis using renewable energy inputs is being actively pursued as a green route for hydrogen production. However, it is limited by the high energy consumption due to the sluggish...

Electrochemical reduction of biomass-derived feedstocks holds great promise to produce value-added chemicals or fuels driven by renewable electricity. However, mechanistic understanding of the aldehyde reduction toward valuable products at the molecular level within the interfacial regions is still lacking. Herein, through tailoring the local environments, including H/D composition and local H 3 O + and H 2 O content, we studied the furfural reduction on Pb electrodes under acid conditions and elucidated the pathways toward three key products: furfuryl alcohol (FA), 2-methylfuran (MF), and hydrofuroin. By combining isotopic labeling and incorporation studies, we revealed that the source of protons (H 2 O and H 3 O + ) plays a critical role in the hydrogenation and hydrogenolysis pathways toward FA and MF, respectively. In particular, the product-selective kinetic isotopic effect of H/D and the surface-property-dependent hydrogenation/deuteration pathway strongly impacted the generation of FA but not MF, owing to their different rate-determining steps. Electrokinetic studies further suggested Langmuir−Hinshelwood and Eley− Rideal pathways in the formation of FA and MF, respectively. Through modifying the double layer by cations with large radii, we further correlated the product selectivity (FA and MF) with interfacial environments (local H 3 O + and H 2 O contents, interfacial electric field, and differential capacitances). Finally, experimental and computational investigations suggested competitive pathways toward hydrofuroin and FA: hydrofuroin is favorably produced in the electrolyte through the self-coupling of ketyl radicals, which are formed from outer-sphere, single-electron transfer, while FA is generated from hydrogenation of the adsorbed furfural/ketyl radical on the electrode surface.

Pairing the electrocatalytic hydrogenation (ECH) reaction with different anodic reactions holds great promise for producing value‐added chemicals driven by renewable energy sources. Replacing the sluggish water oxidation with a bio‐based upgrading reaction can reduce the overall energy cost and allows for the simultaneous generation of high‐value products at both electrodes. Herein, we developed a membrane‐electrode assembly (MEA)‐based electrolysis system for the conversion of 5‐(hydroxymethyl)furfural (HMF) to bis(hydroxymethyl)furan (BHMF) and 2,5‐furandicarboxylic acid (FDCA). With (2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO)‐mediated electrochemical oxidation (ECO) of HMF at the anode, the unique zero‐gap configuration enabled a minimal cell voltage of 1.5 V at 10 mA, which was stable during a 24‐hour period of continuous electrolysis, resulting in a combined faradaic efficiency (FE) as high as 139 % to BHMF and FDCA. High FE was also obtained in a pH‐asymmetric mediator‐free configuration, in which the ECO was carried out in 0.1 M KOH with an electrodeposited NiFe oxide catalyst and a bipolar membrane. Taking advantage of the low cell resistance of the MEA‐based system, we also explored ECH of HMF at high current density (280 mA cm−2), in which a FE of 24 % towards BHMF was achieved. The co‐generated H2 was supplied into a batch reactor in tandem for the catalytic hydrogenation of furfural or benzaldehyde under ambient conditions, resulting in an additional 7.3 % of indirect FE in a single‐pass operation. The co‐electrolysis of bio‐derived molecules and the tandem electrocatalytic‐catalytic process provide sustainable avenues towards distributed, flexible, and energy‐efficient routes for the synthesis of valuable chemicals.

Bismuth nanosheets (BiNSs) have been recognized as a promising catalyst for electrochemical CO 2 reduction (CO 2 RR) to formate, but their preparation typically involves an elaborate synthesis of Bi precursors under elevated temperatures and pressures. Here, we demonstrate a simple surfactant-free method of preparing Bi 2 O 3 -derived BiNSs (OD-BiNSs) by aqueous precipitation and cyclic voltammetry (CV) under ambient conditions. In situ morphology transformation from Bi 2 O 3 to BiNSs was observed during CV, in which the presence of oxygen and the initial morphology of Bi 2 O 3 are crucial for the phase transformation. The as-prepared OD-BiNSs showed 93% of faradic efficiency (FE) to formate with a partial current density of 62 mA cm −2 at −0.95 V RHE in the H-cell and >94% FE at 50−200 mA cm −2 with cell voltages of 2.4−4.0 V in the flow cell.

We describe a method to pattern arbitrary-shaped silane self-assembled monolayers (SAMs) with nm scale resolution using DNA nanostructures as templates. The DNA nanostructures assembled on a silicon substrate act as a soft-mask to negatively pattern SAMs. Mixed SAMs can be prepared by back filling the negative tone patterns with a different silane.