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[Display omitted] • UO 2 were dominated by U(V) after exposure to γ-ray in either H 2 O or 1 M Cl- / Br-. • XPS shows (meta)-studtite formed on UO 2 after exposure to γ-ray in H 2 O. • UPS shows U(VI) on UO 2 after exposure to γ-ray in either H 2 O or 1 M Cl- / Br-. • Br 3 - was observed in 1 M Br- solution exposed to γ-radiation. In this work, we have experimentally studied UO 2 dissolution in pure water and in 1 M aqueous solutions of either Cl- or Br- exposed to γ-radiation. It has previously been found that high ionic strength can facilitate adsorption of dissolved UO 2 2+ on UO 2 surfaces. The adsorption is also affected by the solution pH relative to the point of zero charge of UO 2. In our experiments, Br 3 - was observed in 1 M Br- solution exposed to γ-radiation. Experiments confirmed that Br 3 - can quantitively oxidize UO 2. XPS and UPS were used to characterize potential surface modifications after exposure. The XPS results show that the UO 2 surfaces after exposure to γ-radiation in pure water and in 1 M aqueous solutions of either Cl- or Br- were significantly oxidized with U(V) as the dominating state. U 4f 7/2 and O 1 s spectra of the UO 2 surface after exposure to γ-radiation in pure water demonstrates the formation of uranyl peroxide secondary phases. UPS results indicate that there is a large percentage of U(VI) on the ultra-thin outer layer of UO 2 after exposure to γ-radiation in 1 M aqueous solutions of Br- and Cl-, and 100 % of U(VI) in the pure water case. [ABSTRACT FROM AUTHOR]

[Display omitted] • CuFe 2 O 4 /biochar/Ag 3 PO 4 heterojunction photocatalyst was successfully prepared. • DFT calculations revealed the charge transfer mechanism. • The photo-generated hole protective mechanism was proposed. • The degradation path of phenol is proposed via DFT calculation and GC–MS analysis. Ag 3 PO 4 has an excellent visible light response, but its serious photocorrosion has limited its application in environmental remediation. Here, we constructed a ternary heterojunction photocatalyst (CuFe 2 O 4 /Biochar/Ag 3 PO 4) to inhibit its photocorrosion and enhance photocatalytic activity. Notably, the composite catalyst (0.5 g/L) thoroughly degraded phenol (20 mg/L) at 18 min, and its apparent kinetic constant is fivefold that of pure Ag 3 PO 4. The analysis of XPS, XRD, and cyclic degradation experiments confirmed that the photocorrosion of the heterojunction photocatalyst was significantly suppressed. The enhanced photocorrosion resistance of Ag 3 PO 4 can be ascribed to the rapid transfer and consumption of photoelectrons on the Ag 3 PO 4 surface by biochar and CuFe 2 O 4 , thereby avoiding photocorrosion. Especially, Ag 3 PO 4 as a hole-rich region can protect Ag+ from being reduced. DFT calculations further revealed the electron transfer and anti-photocorrosion mechanism of Ag 3 PO 4. The photogenerated O 2 – and h+ played a major role in phenol degradation. A possible degradation pathway was proposed by DFT calculations and GC–MS analysis. This study provides a novel ternary heterojunction photocatalyst to improve the catalytic performance and photocorrosion resistance of Ag 3 PO 4. [ABSTRACT FROM AUTHOR]

[Display omitted] • The hybrid HTL consists of MoS 2 nanosheets and a PEDOT derivative, which results in an obvious improvement in organic solar cells' performance. • We identified that the synergy of exfoliated-MoS 2 nanosheets and DA-P result in better hole transport and extraction through systematic investigations. • By applying a comprehensive range of spectroscopies, we discovered that the dopant is derived from the oxidation products of MoS 2 nanosheets during ultrasonic exfoliation. We report an efficient hole transporting layer (HTL) for organic solar cell (OSC) based on solution-processed organic-inorganic hybrid composed of ultrasonic-exfoliated MoS 2 nanosheets and dopamine-copolymerized poly(3,4-ethylenedioxythiophene) (PEDOT) derivative (DA-P). The OSCs based on this new hybrid HTL show a marked performance improvement over those with single-component HTLs, and they retain up to 80% of their original power conversion efficiency after 35 days. Our investigations reveal that the boost in performance is due to a synergistic effect that improves both hole transport and extraction ability. This effect is mainly due to the doping of exfoliated-MoS 2 nanosheets on DA-P. We employ a comprehensive range of spectroscopies to uncover that the dopant is derived from the oxidation products of MoS 2 nanosheets during the ultrasonic exfoliation. Our work demonstrates an efficient hybrid HTL and offers new insights into the interaction of exfoliated-MoS 2 nanosheets and the PEDOT derivatives. [ABSTRACT FROM AUTHOR]

• Increased work function of the hybrid interface Si-SiO 2 /organic layer with acidic groups. • Surface band bending of the silicon crystal upward along with a negative surface dipole. • The protonation effect of the silicon oxide film by molecular acidic groups. • Increased depth of space charge region and height of Schottky barrier in Si semiconductor. The large photovoltaic response from homogeneous silicon wafer obtained upon deposition of a molecular layer on its surface remained an unexplained phenomenon so far. Here, we show by X-ray and ultraviolet photoelectron spectroscopy that deposition of species containing acidic groups on the surface of n -type silicon with native silicon oxide overlayer always results in increased work function of the hybrid interface. This effect is shown to originate due to the surface band bending of the silicon crystal upward, which is accompanied by a negative surface dipole formed. This effect is assigned to protonation of the silicon oxide film by molecular acidic groups, which in turn facilitates accumulation of a mirror negative charge at the Si-SiO 2 interface, thus increasing the depth of the depletion region and height of the Schottky barrier in the silicon semiconductor, respectively. Comparison of the work functions of the samples in the dark and under illumination confirms formation of a depletion region at the silicon surface upon molecular adsorption. [ABSTRACT FROM AUTHOR]