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Transition metal carbonate hydroxide (CH) has been widely explored as a promising battery-type electrode for high-rate energy storage. However, its genuine active sites under realistic operating conditions remains elusive. Here, by virtue of the cutting-edge operandoX-ray absorption spectroscopy, we unfold the dynamic evolution of the local electronic and geometric structures for the CH electrode upon cycling. Our results reveal that the irreversible redox of Co cations at the early stage of cyclic voltammetry (CV) cycling induces a phase transition in the NiCo CH nanowires forming oxygen vacancies-enriched NiCo layered double hydroxide (LDH) nanosheets with superior high-rate energy storage ability. Theoretical modeling demonstrates that the unsaturated 5-coordinated Co sites exhibit optimal redox reaction energy barrier and immensely promote the performance. These findings not only elucidate the electrochemical susceptibility of the Co-based carbonate hydroxide under operandoconditions, but also highlight an electrochemical coordination-engineering strategy for the rational design of high-performance electrode.

A hybrid of oxygen-defect-abundant Co3O4−xnanoparticles and graphene was successfully synthesized by a simple one-step laser irradiation method, and N atoms were introduced into the graphene by subsequent hydrothermal treatment. The Co3O4−x/NG exhibits remarkably enhanced OER and ORR catalytic performance compared to Co3O4/NG and a mixture of Co3O4−xand NG, which could be attributed to the oxygen vacancies and the synergistic effect of Co-N-C species. This study can offer a new way for the design and synthesis of OER/ORR bi-functional electrocatalyst.A hybrid of oxygen-defect-abundant Co3O4−x/N-graphene was successfully synthesized by a simple laser irradiation method. The hybrid exhibits remarkably enhanced OER and ORR catalytic performance, which could be attributed to the oxygen vacancies and the synergistic effect of Co-N-C species. This study can offer a new way for the design and synthesis of OER/ORR bi-functional electrocatalyst.

CO2electroreduction provides an effective solution on CO2emission and greenhouse effect. However, it is a big challenge to produce hydrocarbon fuels with high energy density via the electroreduction of CO2. Here we report the efficient production of ethylene by constructing Ag–Cu bimetallic catalyst with sharp interface; the Faradaic efficiency for ethylene formation is enhanced to 42%, more than 2 times that of pure Cu catalyst. The high yield of ethylene can be rationalized by the relay catalysis of Ag and Cu component around the Ag/Cu interface.

Laser ablation in liquid was used to prepare homogeneous copper–zinc alloy catalysts that exhibited excellent selectivity for C2H4in CO2electroreduction, with faradaic efficiency values as high as 33.3% at a potential of −1.1 V (vs reversible hydrogen electrode). The high proximity of Cu and Zn atoms on the surface of the catalyst was found to facilitate both stabilization of the CO* intermediate and its transfer from Zn atoms to their Cu neighbors, where further dimerization and protonation occur to give rise to a large amount of ethylene product. The new homogeneous nanocatalyst, along with the mechanism proposed for its performance, may be very helpful for in-depth understanding of processes related to carbon dioxide electroreduction and conversion.

Graphical Abstract: A hybrid defective nickel-molybdenum bimetallic sulfide is constructed to mimic naturally occurring haloperoxidase, yielding superior antibiofouling ability in bio-aggressive seawater.

The efficiency with which renewable fuels and feedstocks are synthesized from electrical sources is limited at present by the sluggish oxygen evolution reaction (OER) in pH-neutral media. We took the view that generating transition-metal sites with high valence at low applied bias should improve the activity of neutral OER catalysts. Here, using density functional theory, we find that the formation energy of desired Ni4+sites is systematically modulated by incorporating judicious combinations of Co, Fe and non-metal P. We therefore synthesized NiCoFeP oxyhydroxides and probed their oxidation kinetics with in situ soft X-ray absorption spectroscopy (sXAS). In situ sXAS studies of neutral-pH OER catalysts indicate ready promotion of Ni4+under low overpotential conditions. The NiCoFeP catalyst outperforms IrO2and retains its performance following 100 h of operation. We showcase NiCoFeP in a membrane-free CO2electroreduction system that achieves a 1.99 V cell voltage at 10 mA cm–2, reducing CO2into CO and oxidizing H2O to O2with a 64% electricity-to-chemical-fuel efficiency.

Electrochemical reduction of carbon dioxide (CO2RR) to formate provides an avenue to the synthesis of value-added carbon-based fuels and feedstocks powered using renewable electricity. Here, we hypothesized that the presence of sulfur atoms in the catalyst surface could promote undercoordinated sites, and thereby improve the electrochemical reduction of CO2to formate. We explored, using density functional theory, how the incorporation of sulfur into tin may favor formate generation. We used atomic layer deposition of SnSxfollowed by a reduction process to synthesize sulfur-modulated tin (Sn(S)) catalysts. X-ray absorption near-edge structure (XANES) studies reveal higher oxidation states in Sn(S) compared with that of tin in Sn nanoparticles. Sn(S)/Au accelerates CO2RR at geometric current densities of 55 mA cm−2at −0.75 V versus reversible hydrogen electrode with a Faradaic efficiency of 93%. Furthermore, Sn(S) catalysts show excellent stability without deactivation (<2% productivity change) following more than 40 hours of operation.

Photo-corrosion is one of the major obstacles for CdS application in wet chemical fields, and atomic layer deposition (ALD) has been proposed as an effective way to suppress the corrosion. Here, prior to ALD coating, CdS, one facilely corrosive photocatalyst, was synthesized via hydrothermal synthesis to access the fundamental corrosion mechanism and the according corrosive sites. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) demonstrated that the failure of catalytic decomposition of methylene blue originated from the formation of soluble CdSO 4 by oxidizing S 2− of as-prepared CdS. High resolution transmission electron microscopy (HRTEM) further identified the active sites in the V-shaped regions of CdS nanoparticles, confirmed by the simulated electric field distribution. To rationally coat oxides on CdS, the right candidates and their thicknesses have been considered by our tunneling model with transfer matrix method based on quantum mechanism, upon which the thickness of protective layer should be less than 0.5 nm to maintain a high tunneling probability, and thus one cycle of ALD TiO 2 or Al 2 O 3 was proposed to passivate the CdS powder to balance the carrier transportation and corrosion suppression. Based on HRTEM results, we found that the active V-shaped region was covered by ALD oxides (TiO 2 or Al 2 O 3 ). For each case, no soluble CdSO 4 has been found before and after photocatalytic reactions based XPS measurements. Importantly, we noticed that with the passivation of one cycle of ALD, the catalyst's lifetime was elongated up to >14 times higher than that of the as-prepared CdS. [ABSTRACT FROM AUTHOR]

The current fast selective catalytic reduction (fast-SCR) technology shows effectiveness in converting diesel engine generated nitrogen oxides (NOx) to environmentally benign nitrogen (N2) with the aid of the precious metal catalyst platinum. Driven by the previous finding of the low-cost mullite's great superiority over Pt in terms of NO oxidation, a series of Mn-based oxides Sm(Y, Tb, Gd, Lu)Mn2O5are synthesized to identify a general descriptor that governs the catalytic performance. Utilizing soft X-ray absorption characterization and molecular orbital theory, here, we show that the catalytic activity difference presents little dependence on the 3d electron occupancy when the A site element is varied (Sm, Tb, Y, Gd, Lu). Instead, strong p–d hybridization between lattice O and octahedral Mn leads to weak bonding strength between external O* and pyramid Mn and essentially increases the catalytic activity for converting NO to NO2.

We studied the magnetic coupling between magnetic atoms at the O-terminated ZnO(0001̅) surface using first-principles total energy calculations. It was found that the substitutional Co and Mn in the O-terminated ZnO(0001̅) surface tend to occupy the outermost cation layer. Different from the magnetic behaviors between substitutional Co and Mn atoms in bulk ZnO, at O-terminated ZnO(0001̅), due to the presence of surface states, the magnetic atoms display ferromagnetic coupling. On the basis of the analysis of electron density of states, n- and p-type doping could enhance the ferromagnetic coupling between Co and Mn atoms at O-terminated ZnO(0001̅), respectively, in good agreement with previous experimental observations. Our results complement the understanding of the origin of ferromagnetism in ZnO-based diluted magnetic semiconductors.

In this work, we deposited Ag nanoparticles (AgNPs) on ITO films with different thickness using potentiostatic electrodeposition method. Lower film thickness produced AgNPs bigger in size, lower in particle population density and bumpier in surface morphology. The LSPR spectral responses of ITO glass-supported AgNPs were in-situ examined. Refractive index sensitivity of 246 nm/RIU was achieved using an ITO glass with film thickness of 23 nm.

Graphite powders were irradiated by pulsed laser at room temperature and normal pressure and then boiled in perchloric acid. Samples were characterized by high-resolution transmission electron microscopy (HRTEM), electron diffraction pattern (EDP), X-ray diffraction (XRD) pattern, and Raman spectroscopy. The analyses on the HRTEM images, EDP, and XRD show that the diamond particles with a size of about 5 nm are obtained. The shifting and broadening of the diamond peak in Raman spectrum indicate that there are high defect density and residual internal stress in synthetic diamond.

In this work, we deposited Ag nanoparticles (AgNPs) on ITO films with different thickness using potentiostatic electrodeposition method. Lower film thickness produced AgNPs bigger in size, lower in particle population density and bumpier in surface morphology. The LSPR spectral responses of ITO glass-supported AgNPs were in-situ examined. Refractive index sensitivity of 246 nm/RIU was achieved using an ITO glass with film thickness of 23 nm.