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Electrochemical reduction of CO2 and nitrate offers a promising avenue to produce valuable chemicals through the using of greenhouse gas and nitrogen‐containing wastewater. However, the generally proposed reaction pathway of concurrent CO2 and nitrate reduction for urea synthesis requires the catalysts to be both efficient in both CO2 and nitrate reduction, thus narrowing the selection range of suitable catalysts. Herein, we demonstrate a distinct mechanism in urea synthesis, a tandem NO3− and CO2 reduction, in which the surface amino species generated by nitrate reduction play the role to capture free CO2 and subsequent initiate its activation. When using the TiO2 electrocatalyst derived from MIL‐125‐NH2, it intrinsically exhibits low activity in aqueous CO2 reduction, however, in the presence of both nitrate and CO2, this catalyst achieves an excellent urea yield rate of 43.37 mmol ⋅ g−1 ⋅ h−1 and a Faradaic efficiency of 48.88 % at −0.9 V vs. RHE in a flow cell. Even at a low CO2 level of 15 %, the Faradaic efficiency of urea synthesis remains robust at 42.33 %. The tandem reduction procedure was further confirmed by in situ spectroscopies and theoretical calculations. This research provides new insights into the selection and design of electrocatalysts for urea synthesis. [ABSTRACT FROM AUTHOR]

High‐efficient photoelectrocatalytic direct ammonia oxidation reaction (AOR) conducted on semiconductor photoanodes remains a substantial challenge. Herein, we develop a strategy of simply introducing ppm levels of Cu ions (0.5–10 mg/L) into NH3 solutions to significantly improve the AOR photocurrent of bare BiVO4 photoanodes from 3.4 to 6.3 mA cm−2 at 1.23 VRHE, being close to the theoretical maximum photocurrent of BiVO4 (7.5 mA cm−2). The surface charge‐separation efficiency has reached 90 % under a low bias of 0.8 VRHE. This AOR exhibits a high Faradaic efficiency (FE) of 93.8 % with the water oxidation reaction (WOR) being greatly suppressed. N2 is the main AOR product with FEs of 71.1 % in aqueous solutions and FEs of 100 % in non‐aqueous solutions. Through mechanistic studies, we find that the formation of Cu−NH3 complexes possesses preferential adsorption on BiVO4 surfaces and efficiently competes with WOR. Meanwhile, the cooperation of BiVO4 surface effect and Cu‐induced coordination effect activates N−H bonds and accelerates the first rate‐limiting proton‐coupled electron transfer for AOR. This simple strategy is further extended to other photoanodes and electrocatalysts. [ABSTRACT FROM AUTHOR]

Herein we report the vital role of spin polarization in proton‐transfer‐mediated water oxidation over a magnetized catalyst. During the electrochemical oxygen evolution reaction (OER) over ferrimagnetic Fe3O4, the external magnetic field induced a remarkable increase in the OER current, however, this increment achieved in weakly alkaline pH (pH 9) was almost 20 times that under strongly alkaline conditions (pH 14). The results of the surface modification experiment and H/D kinetic isotope effect investigation confirm that, at weakly alkaline pH, during the nucleophilic attack of FeIV=O by molecular water, the magnetized Fe3O4 catalyst polarizes the spin states of the nucleophilic attacking intermediates. The spin‐enhanced singlet O−H cleavage and triplet O−O bonding occur synergistically, which promotes the O2 generation more significantly than the strongly alkaline case involving only spin‐enhanced O−O bonding. [ABSTRACT FROM AUTHOR]

Herein, we fabricated a π–π stacking hybrid photocatalyst by combining two two‐dimensional (2D) materials: g‐C3N4 and a Cu‐porphyrin metal–organic framework (MOF). After an aerobic photocatalytic pretreatment, this hybrid catalyst exhibited an unprecedented ability to photocatalytically reduce CO2 to CO and CH4 under the typical level (20 %) of O2 in the air. Intriguingly, the presence of O2 did not suppress CO2 reduction; instead, a fivefold increase compared with that in the absence of O2 was observed. Structural analysis indicated that during aerobic pretreatment, the Cu node in the 2D‐MOF moiety was hydroxylated by the hydroxyl generated from the reduction of O2. Then the formed hydroxylated Cu node maintained its structure during aerobic CO2 reduction, whereas it underwent structural alteration and was reductively devitalized in the absence of O2. Theoretical calculations further demonstrated that CO2 reduction, instead of O2 reduction, occurred preferentially on the hydroxylated Cu node. [ABSTRACT FROM AUTHOR]

The sluggish H2O oxidation kinetics on photoanodes severely obstructs the overall solar‐to‐energy efficiency of photoelectrochemical (PEC) cells. Herein, we find a 10 to 55‐fold increase of photocurrent by conducting ammonia oxidation reaction (AOR) on hematite (α‐Fe2O3) photoanodes under near‐neutral pH (9–11) and moderate applied potentials (1.0–1.4 VRHE) compared to H2O oxidation. By rate law analysis and operando spectroscopic studies, we confirm the non‐radical nucleophilic attack of NH3 molecules on high‐valent surface Fe−O species (e.g. FeIV=O) and Fe−N species that produces NOx− and N2, respectively, which overwhelms the nucleophilic attack of H2O on surface FeIV=O and contributes to a high Faradaic efficiency of above 80 % for AOR. This work reveals a novel non‐radical nucleophilic attack strategy, which is significantly different from the conventional indirect radical‐mediated AOR mechanism, for the rational design of high‐performance AOR photoelectrocatalysts. [ABSTRACT FROM AUTHOR]

Regulating the distribution of reactive oxygen species generated from H2O2 activation is the prerequisite to ensuring the efficient and safe use of H2O2 in the chemistry and life science fields. Herein, we demonstrate that constructing a dual Cu−Fe site through the self‐assembly of single‐atomic‐layered Cu5 nanoclusters onto a FeS2 surface achieves selective H2O2 activation with high efficiency. Unlike its unitary Cu or Fe counterpart, the dual Cu−Fe sites residing at the perimeter zone of the Cu5/FeS2 interface facilitate H2O2 adsorption and barrierless decomposition into ⋅OH via forming a bridging Cu‐O‐O‐Fe complex. The robust in situ formation of ⋅OH governed by this atomic‐layered catalyst enables the effective oxidation of several refractory toxic pollutants across a broad pH range, including alachlor, sulfadimidine, p‐nitrobenzoic acid, p‐chlorophenol, p‐chloronitrobenzene. This work highlights the concept of building a dual catalytic site in manipulating selective H2O2 activation on the surface molecular level towards efficient environmental control and beyond. [ABSTRACT FROM AUTHOR]

Current plasmonic photocatalysts are mainly based on noble metal nanoparticles and rarely work in the infrared (IR) light range. Herein, cost‐effective Bi2O3−x with oxygen vacancies was formed in situ on commercial bismuth powder by calcination at 453.15 K in atmosphere. Interestingly, defects introduced into Bi2O3−x simultaneously induced a localized surface plasmon resonance (LSPR) in the wavelength range of 600–1400 nm and enhanced the adsorption for CO2 molecules, which enabled efficient photocatalysis of CO2‐to‐CO (ca. 100 % selectivity) even under low‐intensity near‐IR light irradiation. Significantly, the apparent quantum yield for CO evolution at 940 nm reached 0.113 %, which is approximately 4 times that found at 450 nm. We also showed that the unique LSPR allows for the realization of a nearly linear dependence of photocatalytic CO production rate on light intensity and operating temperature. Finally, based on an IR spectroscopy study, an oxygen‐vacancy induced Mars‐van Krevlen mechanism was proposed to understand the CO2 reduction reactions. [ABSTRACT FROM AUTHOR]

An efficient redox reaction between organic substrates in solution and photoinduced h+vb/e−cb on the surface of photocatalysts requires the substrates or solvent to be adsorbed onto the surface, and is consequentially marked by a normal kinetic solvent isotope effect (KSIE≥1). Reported herein is a universal inverse KSIE (0.6-0.8 at 298 K) for the reductive dehalogenation of aromatic halides which cannot adsorb onto TiO2 in a [D0]methanol/[D4]methanol solution. Combined with in situ ATR-FTIR spectroscopy investigations, a previously unknown pathway for the transformation of these aromatic halides in TiO2 photocatalysis was identified: a proton adduct intermediate, induced by released H+/D+ from solvent oxidation, accompanies a change in hybridization from sp2 to sp3 at a carbon atom of the aromatic halides. The protonation event leads these aromatic halides to adsorb onto the TiO2 surface and an ET reaction to form dehalogenated products follows. [ABSTRACT FROM AUTHOR]

No two ways about it: In the photocatalytic deoxygenation of epoxides, the TiO2 particle concertedly transfers two stored electrons to generate a carbanion intermediate, which dissociates to the alkene product. This pathway ensures the higher alkene and stereoselectivity of the photocatalytic deoxygenation than those involving a single‐electron transfer. [ABSTRACT FROM AUTHOR]

The article discusses a study which examines electron reduction of oxygen to H2O in titanium dioxide (TiO2) using pendant proton relay. It says that in photocatalytic aerobic oxidation, oxygen is the fundamental oxidant and the oxygen reduction reaction (ORR) is triggered by conduction band electrons. It ORR is strongly influenced by the different varieties of oxygen. It reveals that surface-pended proton relays control ORR to four-electron reduction in TiO2.

Current plasmonic photocatalysts are mainly based on noble metal nanoparticles and rarely work in the infrared (IR) light range. Herein, cost‐effective Bi2O3−x with oxygen vacancies was formed in situ on commercial bismuth powder by calcination at 453.15 K in atmosphere. Interestingly, defects introduced into Bi2O3−x simultaneously induced a localized surface plasmon resonance (LSPR) in the wavelength range of 600–1400 nm and enhanced the adsorption for CO2 molecules, which enabled efficient photocatalysis of CO2‐to‐CO (ca. 100 % selectivity) even under low‐intensity near‐IR light irradiation. Significantly, the apparent quantum yield for CO evolution at 940 nm reached 0.113 %, which is approximately 4 times that found at 450 nm. We also showed that the unique LSPR allows for the realization of a nearly linear dependence of photocatalytic CO production rate on light intensity and operating temperature. Finally, based on an IR spectroscopy study, an oxygen‐vacancy induced Mars‐van Krevlen mechanism was proposed to understand the CO2 reduction reactions. [ABSTRACT FROM AUTHOR]