Photocatalytic Hydrogen and Oxygen Evolution Performed by a Long-Afterglow Material.

A micron-sized long-afterglow material, Sr2MgSi2O7:Eu,Ce, was utilized to conduct the hydrogen evolution reaction and oxygen evolution reaction, two half-reactions of water splitting, in the presence of sacrificial agents under both light and dark conditions for the first time. The as-synthesized Sr2MgSi2O7:Eu,Ce exhibited higher photocatalytic activity compared to that of the referenced Sr2MgSi2O7:Eu and Sr2MgSi2O7:Ce samples. Herein, in addition to benefiting from the long photogenerated carrier lifetime of long-afterglow materials, the higher photocatalytic activity was attributed to the conjugated electronic structure between Eu and Ce ions. This structure facilitates charge and energy transfer between them, leading to an enhanced photocatalytic efficiency. This research provides a new strategy for designing efficient long-afterglow material photocatalysts through the construction of conjugated electronic structures.

Visible Photocatalytic Hydrogen Evolution by g-C3N4/SrZrO3 Heterostructure Material.

A heterostructure material g-C3N4/SrZrO3 was simply prepared by grinding and heating the mixture of SrZrO3 and g-C3N4. The morphology and structure of the synthesized photocatalysts were determined by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM) and infrared spectra. It showed visible light absorption ability and much higher photocatalytic activity than that of pristine g-C3N4 or SrZrO3. Under the optimal reaction conditions, the hydrogen production efficiency is 1222 µmol·g-1·h-1 and 34 µmol·g-1·h-1 under ultraviolet light irradiation and visible light irradiation, respectively. It is attributed to the higher separation efficiency of photogenerated electrons and holes between the cooperation of g-C3N4 and SrZrO3, which is demonstrated by photocurrent measurements.

N-doped carbon nanotubes supported CoSe2 nanoparticles: A highly efficient and stable catalyst for H2O2 electrosynthesis in acidic media.

Electrocatalytic oxygen reduction reaction (ORR) provides an attractive alternative to anthraquinone process for H2O2 synthesis. Rational design of earth-abundant electrocatalysts for H2O2 synthesis via a two-electron ORR process in acids is attractive but still very challenging. In this work, we report that nitrogen-doped carbon nanotubes as a multi-functional support for CoSe2 nanoparticles not only keep CoSe2 nanoparticles well dispersed but alter the crystal structure, which in turn improves the overall catalytic behaviors and thereby renders high O2-to-H2O2 conversion efficiency. In 0.1 M HClO4, such CoSe2@NCNTs hybrid delivers a high H2O2 selectivity of 93.2% and a large H2O2 yield rate of 172 ppm·h-1 with excellent durability up to 24 h. Moreover, CoSe2@NCNTs performs effectively for organic dye degradation via electro-Fenton process. Electronic Supplementary Material: Supplementary material (SEM images, EDX mapping images, XPS spectrum, XRD patterns, RRDE voltammogram, Tafel plots, cyclic voltammograms, UV-Vis spectra, and Tables S1) is available in the online version of this article at 10.1007/s12274-021-3474-0.

Enriched Surface Oxygen Vacancies of Fe2(MoO4)3 Catalysts for a PDS-Activated photoFenton System.

The environmentally benign Fe2(MoO4)3 plays a crucial role in the transformation of organic contaminants, either through catalytically decomposing oxidants or through directly oxidizing the target pollutants. Because of their dual roles and the complex surface chemical reactions, the mechanism involved in Fe2(MoO4)3-catalyzed PDS activation processes remains obscure. In this study, Fe2(MoO4)3 was prepared via the hydrothermal and calcine method, and photoFenton degradation of methyl orange (MO) was used to evaluate the catalytic performance of Fe2(MoO4)3. Fe2(MoO4)3 catalysts with abundant surface oxygen vacancies were used to construct a synergistic system involving a photocatalyst and PDS activation. The oxygen vacancies and Fe2+/Fe3+ shuttle played key roles in the novel pathways for generation of •O2-, h+, and 1O2 in the UV-Vis + PDS + FMO-6 photoFenton system. This study advances the fundamental understanding of the underlying mechanism involved in the transition metal oxide-catalyzed PDS activation processes.

Cobalt, iron co-incorporated Ni(OH)2 multiphase for superior multifunctional electrocatalytic oxidation.

The cobalt, iron co-incorporated Ni(OH)2 multiphase displays superior catalytic activity and stability for multifunctional electrocatalytic oxidation, ascribed to the multiphase synergy, enhanced charge transfer and well-exposed active sites.

Green preparation of porous hierarchical TiO2(B)/anatase phase junction for effective photocatalytic degradation of antibiotics.

In this study, porous hierarchical bronze/anatase phase junction TiO2 assembled by ultrathin two-dimensional nanosheets was prepared by a novel, green and simple deep eutectic solvent-regulated strategy. Due to its structural features, the TiO2 sample exhibited enhanced photocatalytic activities for multiple kinds of antibiotics, including ofloxacin, ciprofloxacin and chloramphenicol.

NiFe Layered-Double-Hydroxide Nanosheet Arrays on Graphite Felt: A 3D Electrocatalyst for Highly Efficient Water Oxidation in Alkaline Media.

It is of great importance to rationally design and develop earth-abundant nanocatalysts for high-efficiency water electrolysis. Herein, NiFe layered double hydroxide was in situ grown hydrothermally on a 3D graphite felt (NiFe LDH/GF) as a high-efficiency catalyst in facilitating the oxygen evolution reaction (OER). In 1.0 M KOH, NiFe LDH/GF requires a low overpotential of 214 mV to deliver a geometric current density of 50 mA cm-2 (η50 mA cm-2 = 214 mV), surpassing that NiFe LDH supported on a 2D graphite paper (NiFe LDH/GP; η50 mA cm-2 = 301 mV). More importantly, NiFe LDH/GF shows good durability at 50 mA cm-2 within 50 h of OER catalysis testing and delivers a faradaic efficiency of nearly 100% in the electrocatalysis of OER.

An amorphous WC thin film enabled high-efficiency N2 reduction electrocatalysis under ambient conditions.

Ambient electrochemical N2 reduction offers a promising alternative to the energy-intensive Haber-Bosch process towards renewable NH3 synthesis in aqueous media but needs efficient electrocatalysts to enable the N2 reduction reaction (NRR). Herein, we propose that an amorphous WC thin film magnetron sputtered onto a graphite foil behaves as a superb NRR electrocatalyst for ambient NH3 production with excellent selectivity. In 0.5 M LiClO4, it attains a large NH3 yield of 43.37 µg h-1 mg-1cat. and a high faradaic efficiency of 21.65% at -0.10 V vs. reversible hydrogen electrode. Impressively, this catalyst also shows excellent selectivity and strong durability for NH3 formation.

Lanthanum-incorporated ß-Ni(OH)2 nanoarrays for robust urea electro-oxidation.

Lanthanum-incorporated ß-Ni(OH)2 nanosheets display superior catalytic behavior and stability for urea electro-oxidation, which originates from the optimized electronic structure, the downshift of the d-band center and the increased number of exposed active sites.

Photocatalytic Overall Water Splitting by SrTiO3 with Surface Oxygen Vacancies.

Strontium Titanate has a typical perovskite structure with advantages of low cost and photochemical stability. However, the wide bandgap and rapid recombination of electrons and holes limited its application in photocatalysis. In this work, a SrTiO3 material with surface oxygen vacancies was synthesized via carbon reduction under a high temperature. It was successfully applied for photocatalytic overall water splitting to produce clean hydrogen energy under visible light irradiation without any sacrificial reagent for the first time. The photocatalytic overall water splitting ability of the as-prepared SrTiO3-C950 is attributed to the surface oxygen vacancies that can make suitable energy levels for visible light response, improving the separation and transfer efficiency of photogenerated carriers.

Controllable fabrication of TiO2 anatase/rutile phase junctions by a designer solvent for promoted photocatalytic performance.

Herein, novel coin tree-like TiO2 moieties with lots of anatase-rutile phase junctions were constructed by a general, simple, and environmentally friendly strategy. The anatase/rutile ratios can be easily tuned by changing the ratios of the two H-bond donors. Owing to this featured shape, the TiO2 sample displays robust photocatalytic activity and better stability.

CuO@CoFe Layered Double Hydroxide Core-Shell Heterostructure as an Efficient Water Oxidation Electrocatalyst under Mild Alkaline Conditions.

Designing hierarchical electrocatalysts with superior water oxidation performance is highly desirable for the production of renewable chemical fuels. Here, we report the development of a CuO@CoFe layered double hydroxide core-shell heterostructure supported on Cu foil (CuO@CoFe-LDH/CF) as a highly active catalyst electrode for water oxidation under mild alkaline conditions. In a 0.2 M carbonate buffer solution (pH 11), it only needs a small overpotential of 213 mV to achieve 10 mA cm-2, outperforming all reported electrocatalysts at comparable testing conditions. It also shows outstanding long-term durability.

Grey Rutile TiO2 with Long-Term Photocatalytic Activity Synthesized Via Two-Step Calcination.

Colored titanium oxides are usually unstable in the atmosphere. Herein, a gray rutile titanium dioxide is synthesized by two-step calcination successively in a high-temperature reduction atmosphere and in a lower-temperature air atmosphere. The as-synthesized gray rutile TiO2 exhibits higher photocatalytic activity than that of white rutile TiO2 and shows high chemical stability. This is attributed to interior oxygen vacancies, which can improve the separation and transmission efficiency of the photogenerated carriers. Most notably, a formed surface passivation layer will protect the interior oxygen vacancies and provide long-term photocatalytic activity.

Unusual electrochemical N2 reduction activity in an earth-abundant iron catalyst via phosphorous modulation.

Fe-enabled high-performance ambient electrochemical N2 reduction still remains a big challenge. Here, we report the unusual role of phosphorous in modulating the electrochemical N2 reduction activity of an Fe catalyst. An FeP2 nanoparticle-reduced graphene oxide hybrid (FeP2-rGO) attains a large NH3 yield of 35.26 µg h-1 mgcat.-1 (7.06 µg h-1 cm-2) and a high faradaic efficiency of 21.99% at -0.40 V vs. reversible hydrogen electrode in 0.5 M LiClO4, outperforming the FeP-rGO hybrid (17.13 µg h-1 mgcat.-1; 8.57%). Theoretical calculations reveal that FeP2 possesses decreased catalytic activity for the hydrogen evolution reaction, higher N2 adsorption energy, and a larger number of active sites than FeP.

MoS2 Nanosheets Assembled on Three-Way Nitrogen-Doped Carbon Tubes for Photocatalytic Water Splitting.

In this work, a micron-sized three-way nitrogen-doped carbon tube covered with MoS2 nanosheets (TNCT@MoS2) was synthesized and applied in photocatalytic water splitting without any sacrificial agents for the first time. The micron-sized three-way nitrogen-doped carbon tube (TNCT) was facilely synthesized by the calcination of commercial sponge. The MoS2 nanosheets were assembled on the carbon tubes by a hydrothermal method. Compared with MoS2, the TNCT@MoS2 heterostructures showed higher H2 evolution rate, which was ascribed to the improved charge separation efficiency and the increased active sites afforded by the TNCT.

High-Performance N2-to-NH3 Conversion Electrocatalyzed by Mo2C Nanorod.

The synthesis of NH3 is mainly dominated by the traditional energy-consuming Haber-Bosch process with a mass of CO2 emission. Electrochemical conversion of N2 to NH3 emerges as a carbon-free process for the sustainable artificial N2 reduction reaction (NRR), but requires an efficient and stable electrocatalyst. Here, we report that the Mo2C nanorod serves as an excellent NRR electrocatalyst for artificial N2 fixation to NH3 with strong durability and acceptable selectivity under ambient conditions. Such a catalyst shows a high Faradaic efficiency of 8.13% and NH3 yield of 95.1 µg h-1 mg-1 cat at -0.3 V in 0.1 M HCl, surpassing the majority of reported electrochemical conversion NRR catalysts. Density functional theory calculation was carried out to gain further insight into the catalytic mechanism involved.

Cr2O3 Nanoparticle-Reduced Graphene Oxide Hybrid: A Highly Active Electrocatalyst for N2 Reduction at Ambient Conditions.

Electrochemical reduction is an eco-friendly alternative for energy-saving artificial N2 fixation. The development of this process requires efficient N2 reduction reaction (NRR) electrocatalysts to overcome the challenge with N2 activation. We show that a Cr2O3 nanoparticle-reduced graphene oxide hybrid (Cr2O3-rGO) is as an outstanding catalyst for electrochemical N2-to-NH3 conversion under ambient conditions. In 0.1 M HCl, Cr2O3-rGO achieves a high NH3 yield of 33.3 µg h-1 mg-1cat. at -0.7 V vs RHE and a high Faradaic efficiency of 7.33% at -0.6 V vs RHE, with excellent selectivity for NH3 synthesis and stability. Density functional theory calculations were executed to gain further insight into the mechanisms.

Promoted water splitting by efficient electron transfer between Au nanoparticles and hematite nanoplates: a theoretical and experimental study.

An ideal interface model combining a hematite nanoplate-based photoanode with Au nanoparticles (NPs) is proposed for elucidating the specific role of Au NPs in photoelectrochemical performances. The theoretical and experimental results reveal that Au/Fe2O3 nanoplates can lead to an enhanced localized electric field at the metal-semiconductor interface upon the formation of surface plasmon resonance and hot electrons, which can be injected into the conduction band of the semiconductor, thus improving the efficiency of the generation and separation of electron-hole pairs. As expected, the Au/Fe2O3 nanoplate-based photoelectrode possessed a higher carrier density and a photocurrent of 1.7 mA cm-2 and 3.8 mA cm-2 at 1.23 V and 1.5 V vs. RHE, which are nearly 5 times and 30 times larger than that of the Au/Fe2O3 nanocrystals and pristine Fe2O3 nanoplate-based photoelectrodes, respectively.

Enabling the electrocatalytic fixation of N2 to NH3 by C-doped TiO2 nanoparticles under ambient conditions.

The conventional Haber-Bosch process for industrial NH3 production from N2 and H2 is highly energy-intensive with a large amount of CO2 emissions and finding a more suitable method for NH3 synthesis under mild conditions is a very attractive topic. The electrocatalytic N2 reduction reaction (NRR) offers us an environmentally benign and sustainable route. In this communication, we report that C-doped TiO2 nanoparticles act as an efficient electrocatalyst for the NRR with excellent selectivity. In 0.1 M Na2SO4, it achieves an NH3 yield of 16.22 µg h-1 mgcat. -1 and a faradaic efficiency of 1.84% at -0.7 V vs. the reversible hydrogen electrode. Furthermore, this catalyst also shows good stability during electrolysis and recycling tests.

Nanowire of WP as a High-Performance Anode Material for Sodium-Ion Batteries.

The design and development of electrode materials with high specific capacity and long cycling life for sodium-ion batteries (SIBs) is still a critical challenge. In this communication, we report the development of tungsten phosphide (WP) nanowire on carbon cloth (WP/CC) as an anode for SIBs. The WP/CC exhibits superior sodium storage capability with 502 mA h g-1 at 0.1 A g-1 . Moreover, this anode is capable of delivering a long lifespan at 2 A g-1 with an excellent capacity retention of 99 % after 1000 cycles.