NiCo2O4 nanowire array on carbon cloth (NiCo2O4/CC) is proposed as a highly active electrocatalyst for ambient nitrate (NO3−) reduction to ammonia (NH3). In 0.1 m NaOH solution with 0.1 m NaNO3, such NiCo2O4/CC achieves a high Faradic efficiency of 99.0% and a large NH3 yield up to 973.2 µmol h−1 cm−2. The superior catalytic activity of NiCo2O4 comes from its half‐metal feature and optimized adsorption energy due to the existence of Ni in the crystal structure. A Zn‐NO3− battery with NiCo2O4/CC cathode also shows a record‐high battery performance.

We demonstrate that high-quality solid-state 17O (I = 5/2) NMR spectra can be successfully obtained for paramagnetic coordination compounds in which oxygen atoms are directly bonded to the paramagnetic metal centers. For complexes containing V(III) (S = 1), Cu(II) (S = 1/2), and Mn(III) (S = 2) metal centers, the 17O isotropic paramagnetic shifts were found to span a range of more than 10000 ppm. In several cases, high-resolution 17O NMR spectra were recorded under very fast magic-angle spinning (MAS) conditions at 21.1 T. Quantum chemical computations using density functional theory (DFT) qualitatively reproduced the experimental 17O hyperfine shift tensors.

Developing cost-effective and highly efficient bifunctional electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great interest for overall water splitting but still remains a challenging issue. Herein, a self-template route is employed to fabricate a unique hybrid composite constructed by encapsulating cobalt nitride (CoN) nanoparticles within three-dimensional (3D) N-doped porous carbon (CoN NP@N-PC) polyhedra, which can be served as a highly active bifunctional electrocatalyst. To afford a current density of 10 mA cm, the as-fabricated CoN NP@N-PC only requires overpotentials as low as 149 and 248 mV for HER and OER, respectively. Moreover, an electrolyzer with CoN NP@N-PC electrodes as both the cathode and anode catalyst in alkaline solutions can drive a current density of 10 mA cm at a cell voltage of only 1.62 V, superior to that of the Pt/IrO couple. The excellent electrocatalytic activity of CoN NP@N-PC can be mainly ascribed to the high inherent conductivity and rich nitrogen vacancies of the CoN lattice, the electronic modulation of the N-doped carbon toward CoN, and the hierarchically porous structure design.

We present the first DFT-based microkinetic model for the Brønsted acid-catalyzed conversion of glucose to 5-hydroxylmethylfurfural (HMF), levulinic acid (LA), and formic acid (FA) and perform kinetic and isotopic tracing NMR spectroscopy mainly at low conversions. We reveal that glucose dehydrates through a cyclic path. Our modeling results are in excellent agreement with kinetic data and indicate that the rate-limiting step is the first dehydration of protonated glucose and that the majority of glucose is consumed through the HMF intermediate. We introduce a combination of 1) automatic mechanism generation with isotopic tracing experiments and 2) elementary reaction flux analysis of important paths with NMR spectroscopy and kinetic experiments to assess mechanisms. We find that the excess formic acid, which appears at high temperatures and glucose conversions, originates from retro-aldol chemistry that involves the C6 carbon atom of glucose.

Iron porphyrin carbenes (IPCs) are thought to be intermediates involved in the metabolism of various xenobiotics by cytochrome P450, as well as in chemical reactions catalyzed by metalloporphyrins and engineered P450s. While early work proposed IPCs to contain FeII, more recent work invokes a double bond description of the iron carbon bond, similar to that found in FeIV porphyrin oxenes. Here, we report the first quantum chemical investigation of IPC Mössbauer and NMR spectroscopic properties, as well as their electronic structures, together with comparisons to ferrous heme proteins and an FeIV oxene model. The results provide the first accurate predictions of the experimental spectroscopic observables as well as the first theoretical explanation of their electrophilic nature, as deduced from experiment. The preferred resonance structure is FeII←{:C(X)Y}0 and not FeIV={C(X)Y}2-, a result that will facilitate research on IPC reactivities in various chemical and biochemical systems.

The study of high-performance electrocatalysts for driving the oxygen evolution reaction (OER) is important for energy storage and conversion systems. As a representative of inverse-spinel-structured oxide catalysts, nickel ferrite (NiFe 2 O 4 ) has recently gained interest because of its earth abundance and environmental friendliness. However, the gained electrocatalytic performance of NiFe 2 O 4 for the OER is still far from the state-of-the-art requirements because of its poor reactivity and finite number of surface active sites. Here, we prepared a series of atomically thin NiFe 2 O 4 catalysts with different lateral sizes through a mild and controllable method. We found that the atomically thin NiFe 2 O 4 quantum dots (AT NiFe 2 O 4 QDs) show the highest OER performance with a current density of 10 mA cm −2 at a low overpotential of 262 mV and a small Tafel slope of 37 mV decade −1 . The outstanding OER performance of AT NiFe 2 O 4 QDs is even comparable to that of commercial RuO 2 catalyst, which can be attributed to its high reactivity and the high fraction of active edge sites resulting from the synergetic effect between the atomically thin thickness and the small lateral size of the atomically thin quantum dot (AT QD) structural motif. The experimental results reveal a negative correlation between lateral size and OER performance in alkaline media. Specifically speaking, the number of low-coordinated oxygen atoms increases with decreasing lateral size, and this leads to significantly more oxygen vacancies that can lower the adsorption energy of H 2 O, increasing the catalytic OER efficiency of AT NiFe 2 O 4 QDs.

5-Hydroxymethylfurfural oxidation reaction (HMFOR) is regarded as a promising approach to attain biomassderived high-value chemical products. As the HMFOR process is complicated, and the two-step oxidation of the aldehyde group and hydroxyl group in 5-hydroxymethylfurfural (HMF) is typically involved, it is fundamentally significant to understand the different catalytic processes for HMFOR. In this work, we identify direct and synergistic oxidation types for HMFOR on cobalt oxide catalysts. For the direct HMFOR process, Co 3 O 4 was found to have a higher activity for the aldehyde group than for the hydroxyl group due to the higher reaction barrier of hydration in the hydroxyl oxidation. By studying the hydroxyl oxidation behaviors in transition metal oxides, NiO exhibited optimal hydroxyl activity owing to the appropriate OH adsorption energy for alcohol dehydrogenation. Therefore, the optimal HMFOR performance was achieved by accurately introducing Ni into the tetrahedral catalytic sites of cobalt spinel oxides to improve the hydroxyl activity. The integrated catalytic sites enhanced the overall activity of HMFOR with 92.42% FDCA yield and 90.35% faradaic efficiency. This work provides a promising perspective for designing efficient electrocatalysts for HMFOR.

With a dual organocatalytic system involving a chiral phosphoric acid and a dicyanopyrazine-derived chromophore (DPZ) photosensitizer and under the irradiation with visible light, an enantioselective Minisci-type addition of α-amino acid-derived redox-active esters (RAEs) to isoquinolines has been developed. A variety of prochiral α-aminoalkyl radicals generated from RAEs were successfully introduced on isoquinolines, providing a range of valuable α-isoquinoline-substituted chiral secondary amines in high yields with good to excellent enantioselectivities.