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Gold-based co-catalysts are a promising class of materials with potential applications in photocatalytic H 2 O 2 production. However, current approaches with Au co-catalysts show limited H 2 O 2 production due to intrinsically weak O 2 adsorption at the Au site. We report an approach to strengthen O 2 adsorption at Au sites, and to improve H 2 O 2 production, through the formation of electron-deficient Au δ+ sites by modifying the electronic structure. In this case, we report the synthesis of TiO 2 /MoS x -Au, following selective deposition of Au onto a MoS x surface which is then further anchored onto TiO 2 . We further show that the catalyst achieves a significantly increased H 2 O 2 production rate of 30.44 mmol g −1  h −1 in O 2 -saturated solution containing ethanol. Density functional theory calculations and X-ray photoelectron spectroscopy analysis reveal that the MoS x mediator induces the formation of electron-deficient Au δ+ sites thereby decreasing the antibonding-orbital occupancy of Au-O ads and subsequently enhancing O 2 adsorption. This strategy may be useful for rationally designing the electronic structure of catalyst surfaces to facilitate artificial photosynthesis. Photocatalytic H 2 O 2 production using Au is hindered by its inherently weak O 2 adsorption. Herein, the authors modify the electronic structure of Au with MoS x to form electron deficient Au sites to promote O 2 adsorption and H 2 O 2 production.

Lithium bis(fluorosulfonyl)imide-based liquid electrolytes are promising for realizing high coulombic efficiency and long cycle life in next-generation Li-metal batteries. However, the role of anions in the formation of the solid–electrolyte interphase remains unclear. Here we combine electrochemical analyses and X-ray photoelectron spectroscopy measurements, both with and without sample washing, together with computational simulations, to propose the reaction pathways of electrolyte decomposition and correlate the interphase component solubility with the efficacy of passivation. We discover that not all the products derived from interphase-forming reactions are incorporated into the resulting passivation layer, with a notable portion present in the liquid electrolyte. We also find that the high-performance electrolytes can afford a sufficiently passivating interphase with minimized electrolyte decomposition, by incorporating more anion-decomposition products. Overall, this work presents a systematic approach of coupling electrochemical and surface analyses to paint a comprehensive picture of solid–electrolyte interphase formation, while identifying the key attributes of high-performance electrolytes to guide future designs. Li-metal batteries often utilize liquid electrolytes that yield a solid–electrolyte interphase on electrodes; however, the role of anions in interphase formation remains unclear. Now it has been shown that anion-decomposition products provide varying contributions to interphase formation and that high-performance electrolytes balance effective interfacial passivation with minimized degradation.

Transition metal chalcogenides have been identified as low-cost and efficient electrocatalysts to promote the hydrogen evolution reaction in alkaline media. However, the identification of active sites and the underlying catalytic mechanism remain elusive. In this work, we employ operando X-ray absorption spectroscopy and near-ambient pressure X-ray photoelectron spectroscopy to elucidate that NiS undergoes an in-situ phase transition to an intimately mixed phase of Ni 3 S 2 and NiO, generating highly active synergistic dual sites at the Ni 3 S 2 /NiO interface. The interfacial Ni is the active site for water dissociation and OH* adsorption while the interfacial S acts as the active site for H* adsorption and H 2 evolution. Accordingly, the in-situ formation of Ni 3 S 2 /NiO interfaces enables NiS electrocatalysts to achieve an overpotential of only 95 ± 8 mV at a current density of 10 mA cm −2 . Our work highlighted that the chemistry of transition metal chalcogenides is highly dynamic, and a careful control of the working conditions may lead to the in-situ formation of catalytic species that boost their catalytic performance. Transition metal chalcogenides are effective and economical electrocatalysts for the hydrogen evolution reaction in alkaline media, yet active sites and catalytic mechanisms remain unclear. Here the authors use operando spectroscopy to study the in-situ conversion of NiS to highly active Ni 3 S 2 /NiO dual-site catalysts for the alkaline hydrogen evolution reaction.

Preventing the deactivation of noble metal-based catalysts due to self-oxidation and poisonous adsorption is a significant challenge in organic electro-oxidation. In this study, we employ a pulsed potential electrolysis strategy for the selective electrocatalytic oxidation of glycerol to glyceric acid over a Pt-based catalyst. In situ Fourier-transform infrared spectroscopy, quasi-in situ X-ray photoelectron spectroscopy, and finite element simulations reveal that the pulsed potential could tailor the catalyst’s oxidation and surface micro-environment. This prevents the overaccumulation of poisoning intermediate species and frees up active sites for the re-adsorption of OH adsorbate and glycerol. The pulsed potential electrolysis strategy results in a higher glyceric acid selectivity (81.8%) than constant-potential electrocatalysis with 0.7 V RHE (37.8%). This work offers an efficient strategy to mitigate the deactivation of noble metal-based electrocatalysts. Mitigating the deactivation of noble metal-based catalysts caused by self-oxidation and toxic adsorption poses a considerable challenge in organic electro-oxidation. This study addresses the issue by employing a pulsed potential electrolysis approach to selectively electrocatalyze the oxidation of glycerol to glyceric acid using a Pt-based catalyst.

Photocatalytic hybrid carbon nanotubes (CNTs)–mediated Ag-CuBi 2 O 4 /Bi 2 WO 6 photocatalyst was fabricated using a hydrothermal technique to effectively eliminate organic pollutants from wastewater. The as-prepared samples were characterized via Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction patterns (XRD), high-resolution transmission electron microscope (HR-TEM), UV–vis Diffuse Reflectance spectrum (UV–Vis DRS), and photoluminescence (PL) studies. The photocatalytic performance of fabricated pristine and hybrid composites was examined by photo-degradation of toxic dye viz. Rhodamine B (RhB) under visible light. Photo-degradation results revealed that the fabricated Ag-CuBi 2 O 4 /CNTs/Bi 2 WO 6 semiconductor photocatalyst followed pseudo-first-order kinetics and displayed a higher photocatalytic rate, which was found to be approximately 3.33 and 2.35 times higher than the pristine CuBi 2 O 4 and Bi 2 WO 6 semiconductor photocatalyst, respectively. Re-cyclic results demonstrated that the formed composite owns excellent stability, even after five consecutive cycles. As per the matched Fermi level of CNTs in between Ag-CuBi 2 O 4 and Bi 2 WO 6 , carbon nanotubes severed as electron transfer-bridge, Ag doping on CuBi 2 O 4 surface successfully increased photon absorption all across CuBi 2 O 4 surface. Also, it hindered the assimilation of photoinduced electron–hole pairs. The increased photocatalytic efficiency is contributed to the uniform dispersion of photo-generated electron–hole pairs via the construction of an S-scheme system. ROS trapping and ESR experiments suggested that (∙OH) and (O 2 − ∙) were the main radical species for enhanced photo-degradation of RhB dye. The current investigation, from our perspective, highlights the new insights for the fabrication of practical CNTs-mediated S-scheme–based semiconductor photocatalyst for the resolution of environmental issues based on practical considerations.

Highly selective oxidation of methane to methanol has long been challenging in catalysis. Here, we reveal key steps for the promotion of this reaction by water when tuning the selectivity of a well-defined CeO₂/Cu₂O/Cu(111) catalyst from carbon monoxide and carbon dioxide to methanol under a reaction environment with methane, oxygen, and water. Ambient-pressure x-ray photoelectron spectroscopy showed that water added to methane and oxygen led to surface methoxy groups and accelerated methanol production. These results were consistent with density functional theory calculations and kinetic Monte Carlo simulations, which showed that water preferentially dissociates over the active cerium ions at the CeO₂–Cu₂O/Cu(111) interface. The adsorbed hydroxyl species blocked O-O bond cleavage that would dehydrogenate methoxy groups to carbon monoxide and carbon dioxide, and it directly converted this species to methanol, while oxygen reoxidized the reduced surface. Water adsorption also displaced the produced methanol into the gas phase.

Beamline 13 of the Photon Factory has been in operation since 2010 as a vacuum ultraviolet and soft X‐ray undulator beamline for X‐ray photoelectron spectroscopy (XPS), X‐ray absorption spectroscopy (XAS), and angle‐resolved photoelectron spectroscopy (ARPES) experiments. The beamline and the end‐station at branch B have been recently upgraded, enabling microscopic XPS, XAS, and ARPES measurements to be performed. In 2015, a planar undulator insertion device was replaced with an APPLE‐II (advanced planar polarized light emitter II) undulator. This replacement allows use of linear, circular, and elliptical polarized light between 48 and 2000 eV with photon intensities of 109–1013 photons s−1. For microscopic measurements, a toroidal post‐mirror was renewed to have more focused beam with profile sizes of 78 µm (horizontal) × 15 µm (vertical) and 84 µm × 11 µm at photon energies of 100 and 400 eV, respectively. A high‐precision sample manipulator composed of an XYZ translator, a rotary feedthrough, and a newly developed goniometer, which is essential for microscopic measurements, has been used to control a sample specimen in six degrees of freedom, i.e. translation in the X, Y, and Z directions and rotation in the polar, azimuthal, and tilt directions. To demonstrate the performance of the focused beams, one‐ and two‐dimensional XPS and XAS scan measurements of a copper grid have been performed. It was indicated from analysis of XPS and XAS intensity maps that the actual spatial resolution can be determined by the beam size. Beamline BL‐13B of the Photon Factory and the end‐station have been upgraded, enabling microscopic XPS, XAS, and ARPES measurements with a spatial resolution that is comparable with the size of the focused beam. Beam profile evaluation and experimental demonstration of microscopic measurements are presented.

SignificanceCombining ambient pressure X-ray photoelectron spectroscopy experiments and quantum mechanical density functional theory calculations, this work reveals the essential first step for activating CO2 on a Cu surface, in particular, highlighting the importance of copper suboxide and the critical role of water. These findings provide the quintessential information needed to guide the future design of improved catalysts. A national priority is to convert CO2 into high-value chemical products such as liquid fuels. Because current electrocatalysts are not adequate, we aim to discover new catalysts by obtaining a detailed understanding of the initial steps of CO2 electroreduction on copper surfaces, the best current catalysts. Using ambient pressure X-ray photoelectron spectroscopy interpreted with quantum mechanical prediction of the structures and free energies, we show that the presence of a thin suboxide structure below the copper surface is essential to bind the CO2 in the physisorbed configuration at 298 K, and we show that this suboxide is essential for converting to the chemisorbed CO2 in the presence of water as the first step toward CO2 reduction products such as formate and CO. This optimum suboxide leads to both neutral and charged Cu surface sites, providing fresh insights into how to design improved carbon dioxide reduction catalysts.

Hygroscopic and acidic nature of organic hole transport layers (HTLs) insisted to replace it with metal oxide semiconductors due to their favorable charge carrier transport with long chemical stability. Apart from large direct bandgap and high optical transmittance, ionization energy in the range of −5.0 to −5.4 eV leads to use NiO as HTL due to good energetic matching with lead halide perovskites. Analyzing X‐ray photoelectron spectroscopic (XPS) data of NiO, it is speculated that p‐type conductivity is related to the NiOOH or Ni2O3 states in the structure and the electrical conductivity can be modified by altering the concentration of nickel or oxygen vacancies. However, it is difficult to separate the contribution from nonlocal screening, surface effect and the presence of vacancy induced Ni3+ ion due to very strong satellite structure in the Ni 2p XPS spectrum of NiO. Thus, an effective approach to analyze the NiO XPS spectrum is presented and the way to correlate the presence of Ni3+ with the conductivity results which will help to avoid overestimation in finding the oxygen‐rich/deficient conditions in NiO. The shoulder peak of Ni2p XPS spectrum is important to understand p‐type semiconducting behavior. Both the Ni 2p and O 1s XPS spectra shall be carefully recorded with fixed take‐off angle (and/or depending on take‐off angle) and compare results with transport measurements.

Graded bulk-heterojunction (G-BHJ) with well-defined vertical phase separation has potential to surpass classical BHJ in organic solar cells (OSCs). In this work, an effective G-BHJ strategy via nonhalogenated solvent sequential deposition is demonstrated using nonfullerene acceptor (NFA) OSCs. Spin-coated G-BHJ OSCs deliver an outstanding 17.48% power conversion efficiency (PCE). Depth-profiling X-ray photoelectron spectroscopy (DP-XPS) and angle-dependent grazing incidence X-ray diffraction (GI-XRD) techniques enable the visualization of polymer/NFA composition and crystallinity gradient distributions, which benefit charge transport, and enable outstanding thick OSC PCEs (16.25% for 300 nm, 14.37% for 500 nm), which are among the highest reported. Moreover, the nonhalogenated solvent enabled G-BHJ OSC via open-air blade coating and achieved a record 16.77% PCE. The blade-coated G-BHJ has drastically different D-A crystallization kinetics, which suppresses the excessive aggregation induced unfavorable phase separation in BHJ. All these make G-BHJ a feasible and promising strategy towards highly efficient, eco- and manufacture friendly OSCs. Graded bulk-heterojunction organic solar cell with well-defined vertical phase separation has the potential to surpass the classical counterpart, thus the optimisation of this structure is crucial. Here, the authors reveal solvent selection strategies for optimising morphology of the structure, enabling efficient, eco-friendly, and scalable solar cells.