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The large-scale application of proton exchange membrane fuel cells is currently hampered by high cost of commercial Pt catalysts and their susceptibility to poisoning by CO impurities in H

Photocatalysis as a sustainable technology is expected to provide a novel sight for the green synthesis of urea directly using N

Photo/electrocatalytic ammonia synthesis has recently developed fast while the ammonia yields over state-of-the-art photo/electrocatalysts are still very moderate. Such low concentration of synthesized NH3 brings about a challenge to the reliable quantification of the product in photo/electrocatalysis. Notably, we found that the quantitative detection of ammonia concentration below 0.2 ppm is error-prone, which is likely the case happening in the majority of photo/electrocatalytic NH3 synthesis, thus arising concerns about the rationality and accuracy for low-concentration ammonia quantification in these processes. Herein, we discuss the methodology used and analyze the reliability of various detection methods for the detection of trace ammonia in aqueous media. The challenges facing the detection of low concentration of ammonia in photo/electrocatalysis can be overcome by integration with multiple detection methods. According to the data presented, we also propose an effective criterion for precise quantification of ammonia, avoiding the unreasonable comparisons in photo/electrocatalytic ammonia synthesis.

Photocatalysis is an ideal and promising green technology to drive numerous chemical reactions for valued chemicals production under very mild conditions, thereby providing solutions to global energy and environment issues related to burning fossil fuels. Over the past decade, layered double hydroxides (LDHs), as the members in two‐dimensional materials family, have attracted much attention due to their many advantages in photocatalysis, such as facile synthesis, low cost and powerful tunability of composition. In this review, we provide a synthetic overview of recent research advances of LDH‐based photocatalysts, with the main discussion of the design strategies to improve their photocatalytic performance, including component control, defect engineering, hybridization, and topological transformation. Structure‐performance correlations and tailor‐made material synthesis strategies are elaborated to discuss how to realize high‐performance LDH‐based photocatalysts for three important reactions (i.e., water splitting, CO2 conversion, and N2 reduction) to generate desirable solar fuels. Further, the remaining challenges and future perspectives of LDH‐based photocatalysts are summed up, aiming to inspire brand new solutions for pushing forward the development of LDH‐based photocatalysis.

The selective hydrogenation of acetylene to ethylene in ethylene-rich gas streams is an important process in the manufacture of polyethylene. Conventional thermal hydrogenation routes require temperatures above 100 °C and excess hydrogen to achieve a satisfactory C2H2 conversion efficiency. Here, we report a room-temperature electrochemical acetylene reduction system based on a layered double hydroxide (LDH)-derived copper catalyst that offers an ethylene Faradaic efficiency of up to ~80% and inhibits alkane and hydrogen formation. The system affords an acetylene conversion of over 99.9% at a flow rate of 50 ml min−1 in a simulated gas feed, yielding high-purity ethylene with an ethylene/acetylene volume ratio exceeding 105 and negligible residual hydrogen (0.08 vol.%). These acetylene conversion metrics are superior to most other state-of-the-art strategies. The findings therefore conclusively demonstrate an electrochemical strategy as a viable alternative to current technologies for acetylene-to-ethylene conversions with potential advantages in energy and atom economies. The selective semihydrogenation of acetylene in ethylene-rich gas streams is an important process in the manufacture of polyethylene, which is traditionally performed thermocatalytically. Now, a room-temperature electrochemical acetylene reduction system with excellent performance is presented.

Nitrate is an important raw material for chemical fertilizers, but it is industrially manufactured in multiple steps at high temperature and pressure, urgently motivating the design of a green and sustainable strategy for nitrate production. We report the photosynthesis of nitrate from N

A universal atomic layer confined doping strategy is developed to prepare Bi

Designing bifunctional catalysts capable of driving the electrochemical hydrogen evolution reaction (HER) and also H2 evolution via the hydrolysis of hydrogen storage materials such as ammonia borane (AB) is of considerable practical importance for future hydrogen economies. Herein, we systematically examined the effect of tensile lattice strain in CoRu nanoalloys supported on carbon quantum dots (CoRu/CQDs) on hydrogen generation by HER and AB hydrolysis. By varying the Ru content, the lattice parameters and Ru-induced lattice strain in the CoRu nanoalloys could be tuned. The CoRu0.5 /CQDs catalyst with an ultra-low Ru content (1.33 wt.%) exhibited excellent catalytic activity for HER (η=18 mV at 10 mA cm-2 in 1 M KOH) and extraordinary activity for the hydrolysis of AB with a turnover frequency of 3255.4 mol ( H 2 ) mol-1 (Ru) min-1 or 814.7 mol ( H 2 ) mol-1 (cat) min-1 at 298 K, respectively, representing one of the best activities yet reported for AB hydrolysis over a ruthenium alloy catalyst. Moreover, the CoRu0.5 /CQDs catalyst displayed excellent stability during each reaction, including seven alternating cycles of HER and AB hydrolysis. Theoretical calculations revealed that the remarkable catalytic performance of CoRu0.5 /CQDs resulted from the optimal alloy electronic structure realized by incorporating small amounts of Ru, which enabled fast interfacial electron transfer to intermediates, thus benefitting H2 evolution kinetics. Results support the development of new and improved catalysts HER and AB hydrolysis.

Cu2 O, a low-cost, visible light responsive semiconductor photocatalyst represents an ideal candidate for visible light driven photocatalytic reduction of N2 to NH3 from the viewpoint of thermodynamics, but it remains unexplored. Reported here is the successful synthesis of uniformly sized and ultrafine Cu2 O platelets, with a lateral size of Cu 2 O -1 h-1 at λ>400 nm), with the origin of the high activity being long-lived photoexcited electrons in trap states, an abundance of exposed active sites, and the underlying support structure. This work guides the future design of ultrafine catalysts for NH3 synthesis and other applications.

Photocatalytic CO2 reduction holds promise as a future technology for the manufacture of fuels and commodity chemicals. However, factors controlling product selectivity remain poorly understood. Herein, we compared the performance of a homologous series of Zn-based layered double hydroxide (ZnM-LDH) photocatalysts for CO2 reduction. By varying the trivalent or tetravalent metal cations in the ZnM-LDH photocatalysts (M = Ti4+, Fe3+, Co3+, Ga3+, Al3+), the product selectivity of the reaction could be precisely controlled. ZnTi-LDH afforded CH4 as the main reduction product; ZnFe-LDH and ZnCo-LDH yielded H2 exclusively from water splitting; whilst ZnGa-LDH and ZnAl-LDH generated CO. In-situ diffuse reflectance infrared measurements, valence band XPS and density function theory calculations were applied to rationalize the CO2 reduction selectivities of the different ZnM-LDH photocatalysts. The analyses revealed that the d-band center (ed) position of the M3+ or M4+ cations controlled the adsorption strength of CO2 and thus the selectivity to carbon-containing products or H2. Cations with d-band centers relatively close to the Fermi level (Ti4+, Ga3+ and Al3+) adsorbed CO2 strongly yielding CH4 or CO, whereas metal cations with d-band centers further from the Fermi level (Fe3+ and Co3+) adsorbed CO2 poorly, thereby yielding H2 only (from water splitting). Our findings clarify the role of trivalent and tetravalent metal cations in LDH photocatalysts for the selective CO2 reduction, paving new ways for the development of improved LDH photocatalyst with high selectivities to specific products.

In recent years, two-dimensional (2D) semiconductor photocatalysts have been widely applied in water splitting, CO2 reduction, N2 fixation, as well as many other important photoreactions. Photocatalysts in the form of 2D nanosheet possess many inherent advantages over traditional 3D nanopowder photocatalysts, including improved light absorption characteristics, shorter electron and hole migration paths to the photocatalysts’ surface (thus minimizing undesirable electron-hole pair recombination), and abundant surface defects which allow band gap modulation and facilitate charge transfer from the semiconductor to adsorbates. When synergistically exploited and optimized, these advantages can impart 2D photocatalysts with remarkable activities relative to their 3D counterparts. Accordingly, a wide range of experimental approaches is now being explored for the synthesis of 2D photocatalysts, with computational methods increasingly being used for identification of promising new 2D photocatalytic materials. Herein, we critically review recent literatures related to 2D photocatalyst development and design. Particular emphasis is placed on 2D photocatalyst synthesis and the importance of computational studies for the fundamental understanding of 2D photocatalyst electronic structure, band gap structure, charge carrier mobility and reaction pathways. We also explore the practical challenges of using 2D photocatalysts, such as their difficulty to synthesize in large quantity and also their characterization. The overarching aim of this review is to provide a snapshot of recent work targeting high-performance 2D photocatalysts for efficient solar energy conversion, thus laying a firm base for future advancements in this rapidly expanding area of photocatalysis research.

Extracellular vesicles (EVs) are heterogeneous membranous vesicles secreted by living cells that are involved in many physiological and pathological processes as intermediaries for intercellular communication and molecular transfer. Recent studies have shown that EVs can regulate the occurrence and development of tumors by transferring proteins, lipids and nucleic acids to immune cells as signaling molecules. As a new diagnostic biomarker and drug delivery system, EVs have broad application prospects in immunotherapy. In addition, the breakthrough of nanotechnology has promoted the development and exploration of engineered EVs for immune-targeted therapy. Herein, we review the uniqueness of EVs in immune regulation and the engineering strategies used for immunotherapy and highlight the logic of their design through typical examples. The present situation and challenges of clinical transformation are discussed, and the development prospects of EVs in immunotherapy are proposed. The goal of this review is to provide new insights into the design of immune-regulatory EVs and expand their application in cancer immunotherapy.

Approximately 2% of the energy consumed by humans each year is used to make nitrogen-based fertilizers, with ammonia (NH3) production being the most significant contributor to this energy demand. C...

In recent years, single-atom catalysts (SACs) have attracted enormous attention due their effectiveness in promoting a variety of catalytic reactions. However, the ability of SACs to enhance cancer phototherapies has received little attention to date. Herein, we synthesized a metal organic framework (MOF) rich in porphyrin-like single atom Fe(III) centers (denoted herein as porphyrin-MOF or P-MOF) and then evaluated the performance of the P-MOF for cancer treatment by photodynamic therapy (PDT) and photothermal therapy (PTT) under NIR (808 nm) irradiation, as well as photoacoustic imaging (PAI) of tumors. On acccount of the abundance of single atom Fe(III) centers, the P-MOF material demonstrated excellent performance for modulation of the hypoxic tumor microenvironment of Hela cell tumors in mice, while also demonstrating good properties as a photoacoustic imaging (PAI) agent. Density functional theory (DFT) calculations were used to elucidate the superior performance of P-MOF in these applications relative to Fe2O3 (a Fe(III) reference compound). The calculations revealed that the narrow band gap energy of P-MOF (1.31 eV) enabled strong absorption of NIR photons, thereby inducing nonradiative transitions that converted incident light into heat to promote PTT. Further, a facile change of the spin state of the single atom Fe(III) centers in P-MOF under NIR irradiation transformed coordinated triplet oxygen (3O2) to singlet oxygen (1O2), benefiting PDT. This work demonstrates the great future potential of both SACs and MOFs as multifunctional agents for cancer treatment and tumor imaging.

For many two-dimensional (2D) materials, low coordination edges and corner sites offer greatly enhanced catalytic performance compared to basal sites, motivating the search for new synthetic approaches towards ultrathin and ultrafine 2D nanomaterials with high specific surface areas. To date, the synthesis of catalysts that are both ultrathin (monolayer) and ultrafine (lateral size

Single-atom catalysts (SACs), on account of their outstanding catalytic potential, are currently emerging as high-performance materials in the field of heterogeneous catalysis. Constructing a strong interaction between the single atom and its supporting matrix plays a pivotal role. Herein, Ti

To comply with the trend toward green and sustainable development of the fine chemical industry, multitudinous promising technologies (e.g., photocatalysis and electrocatalysis) are beginning to dabble in the green synthesis of fine chemicals, particularly urea synthesis. Whilst numerous advances are made in mechanistic understanding, the low yield reported so far also imposes more stringent requirements on the reliability and anti-interference of the detection method. Herein, the applicability of frequently used methods for urea quantification is methodically compared. In terms of the experimental results, a precise and methodical protocol for urea quantification or evaluation in photo/electrocatalysis is explored and established, with emphasis on screening quantitative methods under specific conditions and indispensable isotopic tracing experiments. The budding urea photo/electrosynthesis urgently demands a rigorous protocol, including the rapid isotopic identification and evaluation criteria, capable of promoting healthy development in the future.

Whilst the photocatalytic technique is considered to be one of the most significant routes to address the energy crisis and global environmental challenges, the solar-to-chemical conversion efficiency is still far from satisfying practical industrial requirements, which can be traced to the suboptimal bandgap and electronic structure of photocatalysts. Strain engineering is a universal scheme that can finely tailor the bandgap and electronic structure of materials, hence supplying a novel avenue to boost their photocatalytic performance. Accordingly, to explore promising directions for certain breakthroughs in strained photocatalysts, an overview on the recent advances of strain engineering from the basics of strain effect, creations of strained materials, as well as characterizations and simulations of strain level is provided. Besides, the potential applications of strain engineering in photocatalysis are summarized, and a vision for the future controllable-electronic-structure photocatalysts by strain engineering is also given. Finally, perspectives on the challenges for future strain-promoted photocatalysis are discussed, placing emphasis on the creation and decoupling of strain effect, and the modification of theoretical frameworks.

Cu

In this work, Zn(OH)F is prepared by an initiative, simple post-synthesis method, in which the molar ratio of F/Zn (R F ) was varied to investigate the effect of the NH 4 F amounts added on the samples. Further, we have mainly investigated their energy bands and photochemical properties. Under UV light irradiation (λ£420 nm), the samples (R F = 0,1,2) show the high degradation activities of methylene blue (MB) dye, namely, 80% of MB can be degraded after 8 min. It is found that the hydroxyl and fluorine have greatly down shifted the conduction band (CB, 0.99 eV) and valence band (VB, 4.17 eV) of Zn(OH)F, compared with ZnO (CB = −0.31 eV, VB = 2.89 eV), but with the nearly same band gap. For the degradation of MB dye, the main oxidative species are holes and hydroxyl radicals for ZnO and Zn(OH)F, respectively. This study suggests that this simple post-synthesis fluorination approach could be extended to develop the other photocatalysts; moreover, we can facilely tune the band structure and photocatalytic activity by introducing or removing hydroxyl and fluorine, which could benefit to develop new photocatalysts.

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.

We have prepared the CoMoO4 nanorods (NR) electrode with a specific capacitance (89.5 F g−1) at a current density of 1 mA cm−2. Moreover, the asymmetric supercapacitor (ASC) has been fabricated by using CoMoO4 NR as positive electrode and activated carbon (AC) as negative electrode. At a power density of 80 mW cm−3, the ASC can deliver an energy density of 0.226 mW h cm−3 in the voltage range of 0–1.6 V. In addition, the CoMoO4 NR-based ASC device still remains a high energy density (84.07%) after 5000 cycles, demonstrating that one-dimensional nanostructures could be promising to achieve the high-energy-density materials.

Electrochemical water splitting into hydrogen and oxygen in neutral electrolytes has great significance for future energy supply security, potentially offering a pathway for H2 generation from seawater. However, the electrocatalytic hydrogen evolution reaction (HER) generally occurs at low rates in neutral solutions due to the low proton concentration in such media. Herein, we fabricated a novel HER catalyst capable of efficient H2 evolution in water at neutral pH, comprising a nickel-molybdenum nitride nanowire array modified with metallic Ni nanoparticles (Ni/NiMoN). The entire Ni/NiMoN array was supported on a Cu foam. The Ni nanoparticles promoted the dissociation of adsorbed water to enhance the supply of protons in the neutral electrolyte, whilst the nanowire array imparted the electrode surface with underwater superaerophobic properties, thus allowing H2 gas bubbles to detach from the electrode in a facile manner. On the basis of the synergies realized between the different electrode components, the Ni/NiMoN nanowire array electrode offered exceptional HER performance, with an overpotential of only 37 mV at a current density of 10 mA cm−2 in a neutral electrolyte. Results guide the development of next-generation earth-abundant element electrocatalysts for HER in neutral media.

Nonmetallic cocatalysts have demonstrated unprecedented potential for accelerating photocatalytic hydrogen evolution reaction (HER). In this study, a nickel phosphide compound, namely Ni5P4, with porous carnation-like superstructure has been target-synthesized and then employed as HER cocatalyst to in-situ build a hybrid with protonated g-C3N4 nanosheets via an electrostatic self-assembly method. Owing to the synergistic advantages of the excellent metallic conductivity and porous carnation-like superstructure of Ni5P4, the as-obtained HCN/Ni5P4 Schottky-junction with abundant active sites, low H* atom adsorption energy and efficient charge carrier transport channel, affords the photocatalytic H2 production rate of 1157.5 μmol g−1 h−1 when exposed to visible light (λ > 420 nm). This photocatalytic H2 production rate was much higher than those of the corresponding reference cocatalysts, namely Ni2P and NiS2 (169.1 and 593.1 μmol g−1 h−1, respectively), both of which were derived from the same Ni(OH)2 precursor. This study provides a new idea for the design of highly active noble-metal-free materials for the photocatalytic HER.