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Nitrate products are widely used in manufacturing as crucial raw materials and fertilizers. The traditional nitrate synthesis process involves high energy consumption and emission, thereby opposing the goals of zero-carbon emission and green chemistry. Thus, a sustainable roadmap for nitrate synthesis that uses green energy input, clean N sources, and direct catalytic processes is urgently required (e.g., developing a novel photosynthesis system). Here, we synthesized TiO2-supported atomically dispersed Cu species for N2 photofixation to nitrate in a flow reactor. The optimized photocatalyst yielded a high nitrate photosynthesis rate of 0.93 μmol h-1 and selectivity of ~90%, which is superior to most of the values reported thus far. Further, experimental results and in-situ investigations revealed that the atomically dispersed Cu sites in the as-designed sample significantly enhanced the separation and transfer efficiency of photogenerated carriers, adsorption and activation of reactants, and the formation of chemisorbed NOx intermediates, thereby realizing the excellent photofixation of N2 to nitrate. [ABSTRACT FROM AUTHOR]

In this paper, the novel straw sheaf-like CuO single crystals have been, for the first time, prepared through a facile two-step process: hydrothermal and subsequent calcination. We have mainly investigated the influences of the copper(II) concentration, the added amount of hexamethylenetetramine (HMT), reaction temperature and time on the samples. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and nitrogen sorption isotherms. The results show that the formed CuO straw sheaves are fairly uniform, and the single straw grows preferentially along the [001] orientation. It is proposed that the CuO straw sheaves form by a crystal splitting growth process. Furthermore, under visible-light irradiation, the CuO straw sheaves exhibit 5.3 times higher activity than the irregular sample for the degradation of rhodamine B (RhB), which has been ascribed to the exposed {110} facets and high crystallinity. [ABSTRACT FROM AUTHOR]

In this work, porous monolayer nickel-iron layered double hydroxide (PM-LDH) nanosheets with a lateral size of ≈30 nm and a thickness of ≈0.8 nm are successfully synthesized by a facile one-step strategy. Briefly, an aqueous solution containing Ni2+ and Fe3+ is added dropwise to an aqueous formamide solution at 80 °C and pH 10, with the PM-LDH product formed within only 10 min. This fast synthetic strategy introduces an abundance of pores in the monolayer NiFe-LDH nanosheets, resulting in PM-LDH containing high concentration of oxygen and cation vacancies, as is confirmed by extended X-ray absorption fine structure and electron spin resonance measurements. The oxygen and cation vacancies in PM-LDH act synergistically to increase the electropositivity of the LDH nanosheets, while also enhancing H2O adsorption and bonding strength of the OH* intermediate formed during water electrooxidation, endowing PM-LDH with outstanding performance for the oxygen evolution reaction (OER). PM-LDH offers a very low overpotential (230 mV) for OER at a current density of 10 mA cm-2, with a Tafel slope of only 47 mV dec-1, representing one of the best OER performance yet reported for a NiFe-LDH system. The results encourage the wider utilization of porous monolayer LDH nanosheets in electrocatalysis, catalysis, and solar cells. [ABSTRACT FROM AUTHOR]

Developing a high energy density micro-supercapacitor still remains a big challenge. In this paper, a two-dimensional (2D) CoMoO4 ultrathin nanosheet (NS)-based asymmetric supercapacitor (ASC) is fabricated. It is found that the CoMoO4 NS electrode processes a high specific capacitance (153.2 F g−1) at a current density of 1 mA cm−2 and this ASC can deliver an energy density of 0.313 mWh cm−3 at a power density of 80 mW cm−3, which is higher than that reported in the literature. Moreover, the ASC can drive a light emitting diode (3 mm diameter, red) to work for 6 min after being charged for 10 s. After 5000 cycles, 77.37% of capacitance still remains. We maintain that the ultrathin thickness can significantly shorten the diffusion paths for both electrons and ions, thus leading to fast electron transport and ion diffusion rates. Our results demonstrate that 2D ultrathin NSs could be a new, promising candidate for energy conversion/storage devices, which could offer more accommodating sites for ion intercalation. [ABSTRACT FROM AUTHOR]

The silicon-doped Bi2O2CO3 nanorods with the interesting hierarchical structure are synthesized by a simple hydrothermal method. The samples are characterized by XRD, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM), Ultraviolet-visible diffuse reflectance spectra (UV-DRS) and nitrogen sorption isotherms. It is found that with the increase of silicon content, the XRD peak of the sample significantly shifts toward a low diffraction angle and the particle morphologies change from nanosheets, nanoflowers to hierarchical nanorods. Moreover, the silicon-doped Bi2O2CO3 hierarchical nanorods exhibit improved photocatalytic degradation activities for different types of dyes under simulated solar light irradiation. The improved activity has been mainly attributed to the unique hierarchical nanorods structure and the formation of Si–O–Bi bonds. [ABSTRACT FROM AUTHOR]

Band gap opening and engineering make up one of the primary goals of developing novel materials for photocatalytic hydrogen generation. We report here a facile synthesis of graphene decorated with in-plane boron nitride domains via control of both the doping sequence of heteroatoms and the oxygen content of the graphene precursor, showing significant differences in the doping pattern compared with B and/or N singly doped or co-doped graphene. We uncover that the formation of BN domains in graphene is critical for engineering the band gap and delivering an improved activity for photocatalytic hydrogen generation in the absence of any photosensitizer. This work paves the way for the rational design and construction of graphene-based photocatalysts for efficient photocatalysis. [ABSTRACT FROM AUTHOR]

Today, research is increasingly focused on surface control of semiconductors; however, very little is known about the effect of bulk chemical bonds on photoelectrochemistry properties. In this report, Bi2O(OH)2SO4 with and without specific Bi-O-S bonds (WB and WOB) is synthesized via hydrothermal and water bath methods, respectively, and we reveal the Bi-O-S bond-dependent photoelectrochemistry properties. Both WB and WOB belong to a monoclinic space group (P21/c), but the newly synthesized WB has different unit cell parameters of a = 8.062 Å, b = 8.384 Å, and c = 5.881 Å, compared with WOB ( a = 7.692(3) Å, b = 13.87(1) Å, c = 5.688(2) Å). Compared with WOB (4.18 eV), WB has a narrower band gap (3.6 eV), higher electrical conductivity, and an increased charge separation efficiency. It is found that the electrons are easy to transfer along the newly formed Bi-O-S bond in bulk; thus, the Bi-O-S bonds in WB have efficiently improved the photoelectrochemistry properties. As a result, WB exhibits a 1.1 times higher photocatalytic activity than WOB for the degradation of RhB under ultraviolet light irradiation (<420 nm). This helps us to understand the photoelectrochemistry properties from crystal bulk, but not merely from the crystal surface; thus, this study provides a new idea for improved photoelectrochemistry properties of semiconductors [ABSTRACT FROM AUTHOR]

Without using any templates, surface-etched Ag3PO4 myriapods were synthesized by a simple glycine complexing method. The unique surface structure endows Ag3PO4 with a high specific surface area, thus leading to greatly improved photocatalytic degradation activity for Rhodamine B compared to that for the solid structures. The glycine complexing strategy is expected to be extended to the preparation of other photocatalysts. [ABSTRACT FROM AUTHOR]