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Graphical abstract Highlights • α-Fe 2 O 3 @g-C 3 N 4 catalyst was synthesized by a facile co-calcination. • It showed excellent photo-Fenton catalytic activity in a wide range of pH. • The high catalytic activity of the catalyst is due to its Z-scheme heterostructure. Abstract Fabricating heterojunction catalysts is a promising strategy for improving the performance in heterogeneous photo-Fenton reaction (PFR). Herein, a Z-scheme heterostructured α-Fe 2 O 3 @g-C 3 N 4 catalyst was successfully synthesized through the co-calcination of melamine and Fe-based MOF. The characterization results demonstrated that α-Fe 2 O 3 nanoparticles anchored on the surface of g-C 3 N 4 successfully. The degradation of tetracycline (TC) in visible-light/H 2 O 2 system was adopted to evaluate the photo-Fenton activity of the catalysts. About 92% of TC was degraded by the optimum composite FOCN-0.45 in 60 min; the degradation rate (0.042 min−1) of TC by the FOCN-0.45 is 6, 7 and 14 times higher than that by pristine MIL-53 (Fe) (0.007 min−1), α-Fe 2 O 3 (0.006 min−1) and g-C 3 N 4 (0.003 min−1), respectively. The prepared FOCN-0.45 composite exhibited excellent performance and high stability in a wide range of pH value. The promoted photo-Fenton catalytic efficiency benefited from the Z-scheme heterojunctions of α-Fe 2 O 3 @g-C 3 N 4 , which enhanced the separation ability of photo-generated charge carriers and increased the electrons that participated in Fe2+/Fe3+ cycle. The boosting OH radicals degraded organic pollutants as main reactive radicals. This work presents a feasible path to design and synthesize heterogeneous photo-Fenton catalysts for the removal of organic pollutants. [ABSTRACT FROM AUTHOR]

Co-doping two metal elements into diamond-like carbon (DLC) films can reach the desirable combined properties, but the preparation and commercialized application of metal co-doped DLC films with well-defined structural properties are currently hindered by the non-comprehensive understanding of structural evolutions under different process parameters. Here, we fabricated the Ti/Al-DLC films using a unique hybrid ion beam system which enabled the independent control of metal content and carbon structure. The evolutions of microstructure, residual compressive stress and mechanical properties induced by the different process parameters including sputtering currents, C 2 H 2 or CH 4 source gases and bias voltages were investigated systematically in order to perform in-depth analysis on the relation between the structure and properties in Ti/Al-DLC films. Results revealed that the variations of process parameters seriously affected the concentration and chemical bond state of co-doped Ti/Al atoms in amorphous carbon matrix or incident energies of C ions, which brought the complicated effect on amorphous carbon structures, accounting for the change of residual compressive stress, hardness and toughness. The present results provide the guidance for suitable, effective parameters selection to tailor the Ti/Al-DLC films with high performance for further applications. [ABSTRACT FROM AUTHOR]

In the independent state, PA and GO are too far away from each other to induce any interactions and energy lowering. Accordingly, the energy of the independent state is calibrated to zero as the energy benchmark, signified by pink dotted line. In the combined state, however, PA and GO draw near to form the stable framework PA-GO driven by energy lowering. Structural diagram of PA, GO and PA-GO are presented as inset. [Display omitted] • Phytic acid functionalized graphene oxide (PA-GO) was facilely fabricated. • C 6 H 6 O 24 P 6 12- is the dominant species of phytic acid in PA-GO fabrication system. • Combination mechanism based on electron transfer induced energy lowering for PA-GO. • PA-GO exhibits high adsorption capacity for ionic dyes in five consecutive cycles. Phytic acid functionalized graphene oxide (PA-GO) has encouraging application in environmental treatment. Herein, structure of PA-GO fabricated by hydrothermal method was inspected. Firstly, the aqueous species distribution and ionization states of phytic acid (PA) and graphene oxide (GO) under varying pH was analyzed according to equilibrium thermodynamics to clarify the primary interacting species involved in PA-GO fabrication. Secondly, the hard-soft acid-base (HSAB) theory and spectroscopic characterizations (XPS, FTIR, Raman, UV–Vis and fluorescent spectra) were employed to elucidate the plausible interactions existing in PA-GO. Thermodynamic deduction indicates, C 6 H 6 O 24 P 6 12- is the dominant species of PA, while –OH and –COO- are the dominant state of graphene oxide groups in PA-GO fabrication system. HSAB theory illuminates, the primary interactions occurs between deprotonated oxygen O(O-) and bridged oxygen O(-O-) of phytic acid with hydroxyl group O(Ar-OH) and π electron of graphene oxide. Moreover, electron flows from GO towards PA to induce energy lowering whereby PA-GO is stabilized. HSAB theory prediction was substantiated by spectroscopic analyses. Furthermore, PA-GO efficiently removes ionic dyes in five consecutive cycles with high adsorption capacity. This work may shed light on the fabrication chemistry of PA-GO framework serving as a potential adsorbent. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mn doping strategy is proposed to enhance the HER activity of MoP for the first time. • Mn doping can optimize the electronic configuration of MoP. • Mn doped MoP is demonstrated as a highly efficient HER catalyst. • The 0.05Mn-MoP exhibits the best HER activity. Rational design of robust and highly efficient electrocatalysts for hydrogen evolution reaction (HER) is crucial for the development of energy conversion technologies. Molybdenum phosphide (MoP) has displayed excellent HER activities and triggered substantial interests as a promising water splitting electrocatalyst. In this work, a Mn doping strategy is proposed to improve the HER performances of MoP for the first time as well as the construction of novel porous interconnected structures. And the effect of doping contents and corresponding improvement mechanism are also discussed. It is found that the obtained 0.05Mn-MoP catalyst with porous interconnected nanosheets (NSs) presents the best HER properties as well as outstanding durability. The porous interconnected structures offer more exposed active sites, and the Mn doping optimizes the electronic configuration of MoP, leading to lower charge transfer resistance and higher intrinsic activity. This work provides a facile method to construct porous structures and demonstrate the effective strategy of Mn doping for the enhancement of MoP for the HER. [ABSTRACT FROM AUTHOR]

• Highly porous Mo 2 C/C is prepared using the N, K co-activated biochar as carbon source and matrix. • The obtained porous Mo 2 C/C shows a large specific surface area with nitrogen doping. • The porous architecture with a large specific surface area can afford abundant catalytic sites. • The interconnected N-rich carbon matrix provides efficient electron transfer pathways for HER. Molybdenum carbide (Mo 2 C) has offered great promise to serve as a platinum substitute towards efficient hydrogen evolution reaction (HER). However, both the lack of exposed catalytic sites and strong Mo–H binding strength will strongly hinder the HER process for Mo 2 C-based electrocatalysts. Herein, a scalable strategy is proposed for the preparation of highly porous Mo 2 C/C electrocatalysts with a specific surface area up to 611 m2 g−1 as well as uniform nitrogen doping derived from N, K co-activated biochar (NKAB). And the porous architecture with a large specific surface area can afford abundant catalytic sites. Additionally, both the Mo 2 C and carbon matrix are doped with nitrogen effectively, which can optimize the hydrogen adsorption free energy of Mo 2 C/C electrocatalysts associated with a higher intrinsic activity. As a result, the active site density and intrinsic activity of Mo 2 C/NKAB have been promoted simultaneously on account of the high specific surface area and nitrogen doping. Furthermore, the interconnected N-rich carbon matrix provides efficient electron transfer pathways for superior HER kinetics. Ultimately, the overall HER performances of Mo 2 C/NKAB can be significantly enhanced. [ABSTRACT FROM AUTHOR]

[Display omitted] • In-situ growth of p-type Ag 2 O on n-type Bi 2 O 2 S surface was achieved. • The heterostructure enhanced the activity of NIR light driven CO 2 photoreduction. • Intimate interfacial contact and heterostructure contributed to the charge transfer. • Ag 2 O/Bi 2 O 2 S exhibited an outstanding ability for adsorption and activation of CO 2. • The reaction mechanism was unveiled based on the experiments and DFT calculations. Photocatalytic converting CO 2 into organic carbon resources holds promise for achieving the utilization of CO 2 resources and the development of clean energy. However, the low utilization efficiency of solar energy and poor separation efficiency of photo-generated carriers limit the application of photocatalytic CO 2 reduction. Herein, Ag 2 O/Bi 2 O 2 S p-n heterojunction photocatalyst (xAO/BOS) was constructed by anchoring Ag 2 O on the surface of Bi 2 O 2 S through in-situ synthesis. The novel 27 %AO/BOS photocatalyst shows the enhanced photocatalytic CO 2 reduction performance with 14.49 μmol g−1 of CO yield and 12.06 μmol g−1 of CH 4 yield after 120 min of NIR light irradiation. The formed p-n heterojunction in 27 %AO/BOS photocatalyst by the in-situ synthesis contributes to facilitating the separation and transfer of photo-generated carriers and improving the adsorption and activation of CO 2. The composite still exhibits excellent photocatalytic cycling stability, and Ag0 species are produced in the photocatalytic CO 2 reduction reaction owing to the in-situ photoreduction of Ag 2 O. Based on the experimental analyses and theoretical calculations, the proposed mechanism for the improved photocatalytic CO 2 reduction activity over in-situ synthesis of 27 %AO/BOS p-n heterojunction photocatalyst is finally given. This work paves a promising way to construct effective NIR light-responsive photocatalysts for CO 2 photoreduction. [ABSTRACT FROM AUTHOR]