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The revival of ternary halides Li-M-X (M = Y, In, Zr, etc.; X = F, Cl, Br) as solid-state electrolytes (SSEs) shows promise in realizing practical solid-state batteries due to their direct compatibility toward high-voltage cathodes and favorable room-temperature ionic conductivities. Most of the reported superionic halide SSEs have a structural pattern of [MCl

Building a reliable relationship between the electronic structure of alloyed metallic catalysts and catalytic performance is important but remains challenging due to the interference from many entangled factors. Herein, a PdBi surface alloy structural model, by tuning the deposition rate of Bi atoms relative to the atomic interdiffusion rate at the interface, realizes a continuous modulation of the electronic structure of Pd. Using advanced X-ray characterization techniques, we provide a precise depiction of the electronic structure of the PdBi surface alloy. As a result, the PdBi catalysts show enhanced propene selectivity compared with the pure Pd catalyst in the selective hydrogenation of propyne. The prevented formation of saturated β-hydrides in the subsurface layers and weakened propene adsorption on the surface contribute to the high selectivity. Our work provides in-depth understanding of the electronic properties of surface alloy structure and underlies the study of the electronic structure-performance relationship in bimetallic catalysts.

This study utilizes the state-of-the-art high energy resolution fluorescence detection (HERFD) and X-ray absorption fine-structure spectroscopy (XAFS) to revisit the Pt L3- and L2-edge whitelines (...

The local structure, many-body effect, and charge redistribution of Pt and Ni in Pt–Ni alloys (Pt–Ni = 3:1, 1:1, and 1:3) have been studied by X-ray absorption spectroscopy and X-ray photoelectron ...

Single atom catalysts exhibit particularly high catalytic activities in contrast to regular nanomaterial-based catalysts. Until recently, research has been mostly focused on single atom catalysts, and it remains a great challenge to synthesize bimetallic dimer structures. Herein, we successfully prepare high-quality one-to-one A-B bimetallic dimer structures (Pt-Ru dimers) through an atomic layer deposition (ALD) process. The Pt-Ru dimers show much higher hydrogen evolution activity (more than 50 times) and excellent stability compared to commercial Pt/C catalysts. X-ray absorption spectroscopy indicates that the Pt-Ru dimers structure model contains one Pt-Ru bonding configuration. First principle calculations reveal that the Pt-Ru dimer generates a synergy effect by modulating the electronic structure, which results in the enhanced hydrogen evolution activity. This work paves the way for the rational design of bimetallic dimers with good activity and stability, which have a great potential to be applied in various catalytic reactions., Atomically precise control over elemental distributions presents a challenge in the preparation of catalytic nanomaterials. Here the authors report Pt-Ru bimetallic dimer structures through atomic layer deposition process and identify the roles of Pt and Ru in hydrogen evolution reaction.

Experimental detection of the Pt 5d densities of states in the valence band is conducted on a series of Pt-Ni alloys by high energy resolution valence-to-core X-ray emission spectroscopy (VTC-XES) at the Pt L3-edge. VTC-XES measurements reveal that the Pt d-band centroid shifts away from the Fermi level upon dilution, accompanied by concentration-dependent Pt d-band width. The competition between the strain effect and ligand effect is observed experimentally for the first time. It is found that the d-band widths in Pt3Ni and PtNi are broader than that of Pt metal due to compressive strain which overcompensates the effect of dilution, while it is narrower in PtNi3 where the ligand effect dominates. VTC-XES is demonstrated to be a powerful tool to study the Pt d-band contribution to the valence band of Pt-based bimetallic. The implication for the enhanced activity of Pt-Ni catalysts in oxygen reduction reaction is discussed.

The utilization of bio-mass waste as valuable materials is of strategic importance to our future. Here, a simple and inexpensive metal-free catalyst was synthesised by employing the bio-waste reed as the single precursor for both carbon (C) and silicon (Si). Interestingly, after the treatment with NH3, the Si element in reed became very active for oxygen reduction reaction (ORR) in alkaline media. The degree of NH3-treatment has a big effect on its ORR performance. Impressively, the onset potential of the optimized sample reaches up to ~1.00 V (vs. reversible hydrogen electrode), the half-wave potential is 0.89 V, and it also shows longer term stability for ORR as compared to commercial Pt/C. Moreover, this reed waste derived Si-N-C metal-free catalyst exhibits excellent performance as an air cathode for a Zn-air battery device. The coexistence of Si and N is essential for the high ORR activity. DFT calculation corroborated this conclusion by indicating that the Si-N structure is essential for the high activity. These new findings will not only open an avenue for the rational design of highly active ORR electrocatalysts, but also symbolize an exciting area for sustainable and low-cost materials for advanced clean energy applications.

Inorganic lead halide perovskite CsPbX3 (X = Cl, Br, or I) nanocrystals are promising candidate materials for light-emitting devices and optoelectronics. Mn-Doped CsPbX3 is of particular interest, as the Mn-doping introduces an additional emission band, making this material a promising white-light emitter. In this study, Mn-doped CsPb(Br/Cl)3 nanocrystals are prepared at room-temperature and ambient pressure. The chemical environment of Mn, and the luminescence of these nanocrystals are analyzed in detail using X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS), X-ray absorption near-edge structure (XANES) and X-ray excited optical luminescence (XEOL). Although the introduction of Mn does not alter the long-range order of the CsPbX3 crystal, it leads to a local lattice contraction with the bond length of Mn–X much shorter than Pb–X. We also find excitation energy-dependence in both the intensity and wavelength of the perovskite excitonic emission band, while only in intensity of the Mn emission band. Detailed fitting of the XEOL reveals that the perovskite emission band is dual-channel, and it is the excitation energy-dependent intensity variation of these two channels that drives the observed red-shift of the combined emission band. Our findings also confirm that the Mn emission band is driven by exciton-Mn energy transfer and clarify the Mn chemical environment and the luminescence mechanism in Mn-doped CsPb(Br/Cl)3 nanocrystals.

Electrochemical reduction of carbon monoxide (CO) has recently been emerging as a potential alternative for converting carbon emission into high-value multi-carbon products such as acetate. Nonetheless, the activity and selectivity for producing acetate have remained low. Herein, we developed an atomically ordered copper-palladium intermetallic compound (CuPd-IC) structure that achieved a high Faradaic efficiency of 70 ± 5% for CO-to-acetate production with a partial current density of 425 mA·cm− 2. This corresponded to an acetate production rate of 4.0 mmol·h− 1·cm− 2, and 5.3 times of enhancement in acetate production compared to pure Cu. Structural characterizations and density functional theory calculations suggested that CuPd-IC presents a high density of Cu-Pd pairs that act as the active sites to enrich the surface CO coverage, stabilize the surface ethenone as a key acetate-path intermediate, and inhibit hydrogen evolution reaction, thus promoting acetate formation. Using a membrane electrode assembly device, the CuPd-IC catalyst enabled 100 hours of CO-to-acetate operation at 500 mA·cm− 2 and an average acetate Faradaic efficiency of 43%, producing ~ 2 mol acetate.

Developing efficient Pt-based electrocatalysts for the methanol oxidation reaction (MOR) is of pivotal importance for large-scale application of direct methanol fuel cells (DMFCs), but Pt suffers from severe deactivation brought by the carbonaceous intermediates such as CO. Here, we demonstrate the formation of a bismuth oxyhydroxide (BiOx(OH)y)-Pt inverse interface via electrochemical reconstruction for enhanced methanol oxidation. By combining density functional theory calculations, X-ray absorption spectroscopy, ambient pressure X-ray photoelectron spectroscopy, and electrochemical characterizations, we reveal that the BiOx(OH)y-Pt inverse interface can induce the electron deficiency of neighboring Pt; this would result in weakened CO adsorption and strengthened OH adsorption, thereby facilitating the removal of the poisonous intermediates and ensuring the high activity and good stability of Pt2Bi sample. This work provides a comprehensive understanding of the inverse interface structure and deep insight into the active sites for MOR, offering great opportunities for rational fabrication of efficient electrocatalysts for DMFCs.

Multi-carbon alcohols such as ethanol are valued as fuels in view of their high energy density and ready transport. Unfortunately, the selectivity toward alcohols in CO2/CO electroreduction is diminished by ethylene production, especially when operating at high current densities (>100 mA cm−2). Here we report a metal doping approach to tune the adsorption of hydrogen at the copper surface and thereby promote alcohol production. Using density functional theory calculations, we screen a suite of transition metal dopants and find that incorporating Pd in Cu moderates hydrogen adsorption and assists the hydrogenation of C2 intermediates, providing a means to favour alcohol production and suppress ethylene. We synthesize a Pd-doped Cu catalyst that achieves a Faradaic efficiency of 40% toward alcohols and a partial current density of 277 mA cm−2 from CO electroreduction. The activity exceeds that of prior reports by a factor of 2., The electrocatalytic upgrading of CO to higher-value fuels provides a promising route to multi-carbon alcohol products. Here, the authors show that high alcohol selectivity and activity can be achieved by incorporating palladium in copper.

Adenosine triphosphate (ATP) biomolecules play critial roles in the biomineralization process during the formation of amorphous calcium phosphate composites (ACPC), and ACPC is an important drug carrier due to its significant advantages of biocompatibility and biodegradability. Hence, studying the behavior of ACPC nanodrug carriers is crucial to investigate the structural regulation of biomimetic minerals and calcium phosphate (CaP)-based drug delivery systems. However, it is difficult to probe these interactions using traditional characterization methods. In this paper, XANES analysis together with STXM successfully provided a method to reveal the interaction of ATP and drug molecules with individual mesoporous ACPC. We found that the adenosine and phosphate groups of ATP biomolecules coordinated with Ca2+ and played critical roles in the formation of ACPC; drug molecules with the -COOH groups were linked to Ca2+via carboxylic acid groups primarily by electrostatic interactions, and the N-containing ring structures within the drug molecules also coordinated with Ca2+.

Highly-efficient CeO2-TiO2-based catalyst is an attractive alternative to traditional V2O5-based catalysts for selective catalytic reduction of NOx by NH3 (NH3-SCR). Herein, we construct an efficient and stable P-doped CeO2/TiO2 (yCeTi-Px) catalyst by dispersing CeO2 on strongly acidic and highly stable mesoporous P-doped TiO2 (Ti-Px). The characteristic structure of Ti-Px causes highly dispersed CeO2, strong active component-support interaction, and abundant surface active oxygen and acid sites on CeTi-P catalyst. Therefore, yCeTi-Px catalyst exhibits much higher catalytic activity than yCeTi catalyst at temperature of 200–450 °C. The yCeTi-Px catalysts show high activity in the presence of H2O and strong resistance to H2O + SO2 at medium-high temperature, implying that they have great industrial application prospects. Different P/Ti ratio and CeO2 loading content were investigated. Excessive P doping can block the Ce4+/Ce3+ redox couple, and suppress redox sites on yCeTi-Px catalyst. Additionally, increasing CeO2 content can reduce the NH3 capacity of yCeTi-Px catalyst. By controlling the P/Ti ratio and CeO2 loading content, surface acid sites and redox sites on yCeTi-Px catalyst can be balanced to obtain the best catalytic activity. This work demonstrates a feasible method in adjusting acid sites and redox sites on CeTi catalyst, which ultimately contributes to the new design of CeO2-TiO2-based catalyst.

Novel FeOOH and Fe 2 O 3 co-grafted TiO 2 photocatalysts were synthesized and tested for bisphenol A (BPA) degradation in water under simulated solar and visible light irradiations. The grafting temperature was simply controlled to adjust the FeOOH and Fe 2 O 3 compositions, with 55 °C being the optimal temperature that led to the highest BPA degradation. Co-grafted FeOOH and Fe 2 O 3 on TiO 2 is advantageous over mono-grafted or un-grafted TiO 2 , because FeOOH promotes BPA adsorption and Fe 2 O 3 enhances photocatalytic activity by facilitating the interfacial charge transfer. Findings from this study contribute to the fabrication of efficient, low-cost photocatalysts for water pollutant removal.

In this work, anatase nanorods (ANR) of TiO2 with active facet {100} as the major facet were successfully synthesized, and reducing the ANR by NaBH4 led to the formation of gray colored oxygen deficient TiO2-x (ReANR). On the surface of ReANR, a thin layer of Al2O3 was deposited using atomic layer deposition (ALD), and the thickness of Al2O3 varied by the number of ALD cycles (1, 2, 5, 10, 50, 100, or 200). The growth rate of Al2O3 was determined to be 0.25 A per cycle based on high-resolution TEM analysis, and the XRD result showed the amorphous structure of Al2O3. All the synthesized photocatalysts (ANR, ReANR, and Al2O3 coated ReANR) were tested for CO2 photocatalytic reduction in the presence of water vapor, with CO detected as the major reduction product and CH4 as the minor product. Compared with ANR, ReANR had more than 50% higher CO production and more than ten times higher CH4 production due to the oxygen vacancies that possibly enhanced CO2 adsorption and activation. By applying less than 5 cycles of ALD, the Al2O3 coated ReANR had enhanced overall production of CO and CH4 than uncoated ReANR, with 2 cycles being the optimum, about 40% higher overall production than ReANR. Whereas, both CO and CH4 production decreased with increasing number of ALD cycles when more than 5 cycles were applied. Photoluminescence (PL) analysis showed an ultrathin layer of Al2O3 (2 cycles of ALD) coating on the ReANR was able to reduce the charge carrier recombination rate, likely because of the passivation of surface states. On the other hand, a relatively thick layer of Al2O3 may act as an insulation layer to prohibit electron migration to the catalyst surface. This work gives valuable insights on the application of ALD coating on photocatalysts to promote CO2 photoreduction to fuels.

Membrane fouling caused by natural organic matters such as humic acid has been one of the major obstacles inhibiting the wide application of membrane technologies for water treatment. In this work, a novel membrane made of interconnecting TiO 2 nanowires, Fe 2 O 3 nanoparticles, and graphene oxide (GO) sheets was prepared via a simple hydrothermal, colloidal blending, and vacuum filtration method. Membrane performance of humic acid removal under simulated solar irradiation and in the dark were compared for membranes with different Fe 2 O 3 /TiO 2 /GO compositions. It was demonstrated that enhanced humic acid removal was achieved due to the greater adsorption of humic acid by Fe 2 O 3 nanoparticles and the improved photocatalytic activity of TiO 2 by the GO sheets that can facilitate separation of photo-induced electron-hole. An optimal Fe 2 O 3 :TiO 2 :GO weight ratio of 50:100:10 was identified, and over 98% humic acid removal was achieved in a short-term test (2 h) and 92% removal in a 12 h test under solar irradiation. By contrast, only 51% humic acid removal was obtained by the same membrane in dark in the 12 h test. A lower pressure drop across the membrane was also observed under solar irradiation (20 kPa) compared with that in the dark (50 kPa). This nanomaterial-based novel membrane contributes to the development of a more effective water treatment technology.

Inorganic lead halide perovskite CsPbX3 (X = Cl, Br, or I) nanocrystals are promising candidate materials for light-emitting devices and optoelectronics. Mn-Doped CsPbX3 is of particular interest, as the Mn-doping introduces an additional emission band, making this material a promising white-light emitter. In this study, Mn-doped CsPb(Br/Cl)3 nanocrystals are prepared at room-temperature and ambient pressure. The chemical environment of Mn, and the luminescence of these nanocrystals are analyzed in detail using X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS), X-ray absorption near-edge structure (XANES) and X-ray excited optical luminescence (XEOL). Although the introduction of Mn does not alter the long-range order of the CsPbX3 crystal, it leads to a local lattice contraction with the bond length of Mn-X much shorter than Pb-X. We also find excitation energy-dependence in both the intensity and wavelength of the perovskite excitonic emission band, while only in intensity of the Mn emission band. Detailed fitting of the XEOL reveals that the perovskite emission band is dual-channel, and it is the excitation energy-dependent intensity variation of these two channels that drives the observed red-shift of the combined emission band. Our findings also confirm that the Mn emission band is driven by exciton-Mn energy transfer and clarify the Mn chemical environment and the luminescence mechanism in Mn-doped CsPb(Br/Cl)3 nanocrystals.

This work for the first time reports engineered oxygen-deficient, blue TiO2 nanocrystals with coexposed {101}-{001} facets (TiO2–x{001}-{101}) to enhance CO2 photoreduction under visible light. The TiO2–x{001}-{101} material demonstrated a relatively high quantum yield (0.31% under UV–vis light and 0.134% under visible light) for CO2 reduction to CO by water vapor and more than 4 times higher visible light activity in comparison with TiO2 with a single {001} plane or {101} plane and TiO2(P25). Possible reasons are the exposure of more active sites (e.g., undercoordinated Ti atoms and oxygen vacancies), the facilitated electron transfer between {001} and {101} planes, and the formation of a new energy state (Ti3+) within the TiO2 band gap to extend the visible light response. An in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) study was applied to understand the roles of coexposed {001}-{101} facets and Ti3+ sites in activating surface intermediates. The in situ DRIFTS analysis ...

CsPbCl3 perovskite nanocrystals are doped with heterovalent Pr3+ using hot-injection method. These Pr3+-doped CsPbCl3 nanocrystals exhibit a dramatically improved absolute photoluminescence quantum yield (PLQY) compared to the undoped CsPbCl3, reaching 78.9 % PLQY at 9 % Pr-substitution. The crystal structure modification upon Pr3+ doping and luminescence mechanism are investigated using conventional optical spectroscopy and synchrotron X-ray spectroscopy (i.e., X-ray absorption fine structure and X-ray excited optical luminescence). Both the Pr3+ and Cl− are found contributing to the luminescence enhancement, and their individual roles in luminescence enhancement are analyzed.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Photocatalytic conversion of CO2 with H2O to solar fuels is a promising technology to recycle CO2, a major greenhouse gas. However, the CO2-to-fuel conversion efficiency is typically low, mainly due to the fast recombination of photo-excited electron-hole pairs and limited absorption of solar spectrum by the photocatalyst. Some scientific challenges that have been overlooked in the literature are the photocatalyst’s ability to adsorb, activate and dissociate CO2, as well as the adsorption/desorption kinetics on the catalyst surface. To solve these problems, we have designed a new multifunctional material, porous microsphere MgO/TiO2 that performs as a hybrid adsorbent/photocatalyst, and we operated the CO2 photo-conversion temperature at around 150 oC. The higher reaction temperature enhanced intermediate/product desorption, and the addition of MgO improves CO2 adsorption at the MgO-TiO2 interface, particularly in the presence of water vapor. This multifunctional material demonstrated a significantly enhanced and more stable activity than pure TiO2 for CO2 photoreduction to CO. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) study was applied to identify surface intermediates and study the kinetics that is a critical factor governing the activity and stability of the photocatalyst. The effects of MgO morphology and dispersion on the TiO2 surface are also investigated.