Hydrogen generation by seawater electrolysis is a sustainable approach to renewable-energy conversion which requires efficient catalyst to address challenges such as competing chlorine evolution reaction, chloride corrosion, and catalyst poisoning. Here, core-shell-structured CoPx@FeOOH is designed for selective OER in seawater. This catalyst has high conductivity, large surface area, improved turnover frequency, and optimal absorption energy to OER intermediates, which together lead to excellent catalytic activity. The enhanced chemical stability and corrosion resistance ensure its catalytic performance in seawater. Specifically, it requires overpotentials of 283 and 337 mV to attain current densities of 100 and 500 mA cm-2, respectively, in 1 M KOH seawater, with durability over 80 h of continuous testing without producing any hypochlorite. The CoPx||CoPx@FeOOH pair requires voltages of 1.710 and 1.867 V to attain current densities of 100 and 500 mA cm-2 with a high Faradaic efficiency, showing its great promise for fuel-gas production from seawater.

Nanomaterials exhibit unique chemical and physical properties in comparison with their bulk-phase counterparts, attracting significant attention from the oil and gas industry in the hope of solving challenging issues.Current heavy oil extraction methods are costly and have unsatisfactory efficiency, and facing environmental restrictions increasingly.Our recent introduction of sodium (Na) nanofluid provides a promising method for heavy oil extraction since it shows improved oil recovery without burning carbon-containing fuels.Here, we conducted coreflooding tests to further evaluate the effect of this Na nanofluid on recovering oil from different formations, which had not been previously demonstrated, as well as to deepen our understanding of the underlying mechanisms.The Na nanofluid exhibited excellent oil-extraction efficiency for both types of heavy oil tested.The recovery mechanisms were found to be complicated.We also found that post-injection soaking and using the proper solvent to disperse the sodium nanoparticles are important for further boosting oil recovery.

As reserves of conventional light oil become depleted, recovery of viscous oil is urgently needed to meet increasing energy demands worldwide before clean energy sources are fully developed. Current oil extraction technologies suffer from low efficiency, high cost, and environmental concerns. Attempts to use nanotechnology in this field have thus far been recognized to have only auxiliary effects, rather than playing a major role. Here we report a reactive sodium nanoparticle fluid able to in situ recover highly viscous crude oil very effectively even at room temperature. Its high recovery performance is based on a chemical reaction that allows the nanofluid to exhibit multiple benefits in displacing subsurface oil: heat, hydrogen gas, and sodium hydroxide. In addition, multi-stage nanofluid injection is found to be superior to a single injection mode. Thus, it opens a new way to extract and process crude oil.

Water electrolysis provides a promising route to produce high energy density hydrogen. Compared with the limited amount of fresh water, seawater is an abundant resource that has attracted increasing attention for electrolysis. However, seawater electrolysis has thus far suffered from degraded activity and stability, and from low oxygen evolution reaction (OER) selectivity, due to the existence of chloride ions and insoluble solids in seawater. This short review summarizes trends in the rational design of OER catalysts, providing some effective strategies, including constructing 3D hierarchical porous structures, employing protective layers, and engineering surface wettability, to synthesize efficient and stable OER catalysts for seawater electrolysis. Finally, a perspective regarding designing high-performance catalysts for seawater electrolysis is also provided.

Pickering emulsions show great promise for many applications in the oil and gas industry. However, the thermal stability of Pickering emulsions reported thus far has been unfavorable for safe operation in the always high-temperature deep underground condition. Here we report a Pickering water-in-oil (W/O) emulsion that exhibits high temperature tolerance in the absence of any surfactant due to the synergistic effect between organoclay and silica nanoparticles (NPs) with intermediate hydrophobicity. The interaction between silica NPs and organoclay was characterized by X-ray diffraction, thermogravimetric analysis, zeta potentials, scanning electron microscopy and transmission electron microscopy. The results of gel volume and water contact angle measurement confirmed the hydrophobicity of the organoclay. The effects of varying the hydrophobicity and concentration of the silica NPs, the clay concentration of the organoclay, and the thermal-rolling temperature on the emulsion stability, droplet size, morphology, and rheology were investigated in detail. The optimal synergy for stabilizing the W/O emulsion was found to occur with 1 wt% silica NPs exhibiting intermediate hydrophobicity and 1 wt% organoclay. As expected, neither hydrophobic nor hydrophilic silica NPs could improve the emulsion stability due to inefficient adsorption at the water-oil interface. Organoclay was found to have a significant influence on the stability and rheological properties of the W/O Pickering emulsion since it dominates the formation of networks in the continuous phase due to its excellent swelling and exfoliation. The adsorption of silica NPs further enhanced the interactions between the particles and the medium, making it possible for the retainment of rheology even after thermal rolling at 220 ℃. The increase in temperature tolerance achieved through a simple and environmentally friendly method makes this Pickering emulsion applicable in potential drilling fluids for the oil and gas field.

Developing high‐performance and cost‐effective bifunctional electrocatalysts for large‐scale water electrolysis is desirable but remains a significant challenge. Most existing nano‐ and micro‐structured electrocatalysts require complex synthetic procedures, making scale‐up highly challenging. Here, a heterogeneous Ni2P‐Fe2P microsheet is synthesized by directly soaking Ni foam in hydrochloric acid and an iron nitrate solution, followed by phosphidation. Benefiting from high intrinsic activity, abundant active sites, and a superior transfer coefficient, this self‐supported Ni2P‐Fe2P electrocatalyst shows superb catalytic activity toward overall water splitting, requiring low voltages of 1.682 and 1.865 V to attain current densities of 100 and 500 mA cm−2 in 1 m KOH, respectively. Such catalytic performance is superior to the benchmark IrO2 || Pt/C pair and also places this electrocatalyst among the best bifunctional catalysts reported thus far. Furthermore, its enhanced corrosion resistance and hydrophilic surface make it suitable for seawater splitting. It is able to achieve current densities of 100 and 500 mA cm−2 in 1 m KOH seawater at voltages of 1.811 and 2.004 V, respectively, which, together with its robust durability, demonstrates its great potential for realistic seawater electrolysis. This work presents a general and economic approach toward the fabrication of heterogeneous metallic phosphide catalysts for water/seawater electrocatalysis.

Nanoparticle-stacked tungsten-doped nickel iron layered double hydroxide (Ni–Fe–W LDH) nanosheets have been synthesized through a facile water bath reaction as efficient water oxidation catalyst.

A strategy inspired by plant growth was applied as a novel and facile way to fabricate nanoscale composites for high-performance electrodes employed in supercapacitors. A binder-free cactus-like nanostructure CoNiO2@Co3O4@Co2N grown on N-doped reduced graphene oxide (rGO)-wrapped nickel foam, in which the N-doped rGO sheet acts as the ground, providing active sites for the composite to grow, and the nickel foam acts as the root system, providing both Ni ions to form the bimetal oxide CoNiO2 and storage for the electrolyte ions, was designed. As the active material, the nanostructured CoNiO2@Co3O4@Co2N not only provides more ion-accessible surfaces but also contributes its battery-mimicking faradaic reaction to the high electrochemical performance of the as-prepared electrode. The synergistic effects of the nanostructure, materials, and energy storage mechanism result in the high capacitance [2615.32 F g(-1) (6.76 F cm(-2))] and excellent rate performance of the as-prepared electrode. This in situ growth system also provides a novel design concept to obtain effective, environmental friendly, and inexpensive composite materials for high-performance energy storage devices. (c) 2019 Elsevier Ltd. All rights reserved.

A robust oxygen-evolving electrocatalyst for high-performance seawater splitting was developed using a cost-effective and industrially compatible method.

Smart Pickering emulsions show great promise for many applications in the oil and gas industry, especially those with pH-responsive behavior that allows them to be easily implemented. However, the pH-responsive emulsion systems reported thus far suffer from a narrow pH window in the stabilization of emulsions, which is less favorable for complicated reservoir conditions. Here we report a smart Pickering water-in-oil (W/O) emulsion system with a wide pH window, based on manipulation of the interactions between fumed silica nanoparticles (NPs) and amine surfactant. The pH-dependent interaction between NPs and amine surfactant was experimentally confirmed by FTIR spectroscopy, turbidity, surface tension, etc. The stable W/O emulsions generated by this system are formed within the range of pH that shows strong flocculation of nanoparticles due to the adsorption of surfactant onto the particle surfaces, which imparts a certain hydrophobicity to the NPs. Outside of the pH window, the similar charge of the NPs and the surfactant generates strong repulsion between them, so the fumed silica NPs cannot be endowed with such hydrophobicity. Due to their highly hydrophilic nature at such pH values, the NPs are not able to stably remain at the immiscible fluid interface, and thus the emulsion system is destabilized. The pH-responsive Pickering emulsion-based drilling fluid shows adjustable rheological properties and is reversible by a cyclic emulsification-demulsification process. We anticipate that this system can be switched “on” over a wide pH range with high stability when running underground and switched “off” in follow-up procedures and waste disposal at the surface.

Pickering emulsions show great potential for the petroleum industry, especially those that can realize emulsion inversion in basic conditions. Developing a simple and green approach to control emulsion inversion in basic conditions is highly desirable for harsh conditions and complicated operations. Here we report novel phase inversion of a Pickering emulsion through the controlled wettability of silica nanoparticles (NPs) by N-(2-((2-aminoethyl)amino)ethyl)octadecenamide (C(18)PDA) with Na2CO3 salt addition. A transitional phase inversion from an oil-in-water (O/W) emulsion to a water-in-oil (W/O) emulsion occurs with increasing C(18)PDA surfactant concentration for a given amount of Na2CO3 salt. A subsequent phase inversion from a W/O emulsion to an O/W emulsion then occurs with increasing Na2CO3 salt concentration at a low amount of C(18)PDA surfactant, and demulsification occurs when the Na2CO3 salt concentration is above 94 mM. The stable W/O Pickering emulsions are formed by virtue of adsorption of the C(18)PDA surfactant onto the silica surfaces, which imparts hydrophobicity to the inherently hydrophilic silica NPs and facilitates strong flocculation of the silica particles in the polar solution. However, the hydrophobicity of the silica NPs is reduced by salinity and is suitable for creating O/W emulsions due to the reduced interactions between the NPs and the C(18)PDA surfactant. The possible mechanism for emulsion inversion was investigated by characterizing turbidity, surface tension, contact angle, Fourier transform infrared spectroscopy with thermogravimetric analysis, zeta potentials, etc. The rheological properties of the reversible Pickering emulsion show that there is a smooth transition at the transitional inversion point, which differs from conventional surfactant-stabilized emulsions, in which the viscosity decreases to the minimum at the transitional inversion point. The emulsion phase inversion was also found to be conducive to improving the efficiency of filter-cakes cleanup. We anticipate this smart system to be easily operated and environmentally friendly, making it potentially applicable to real oil fields.

Bi-Sb-Te-based semiconductors possess the best room-temperature thermoelectric performance, but are restricted for application in the wearable field because of their inherent brittleness, rigidity, and nonscalable manufacturing techniques. Therefore, how to obtain thermoelectric materials with excellent thermoelectric properties and flexibility through the batch production process is a serious challenge. Here, we report the fabrication of flexible p-type thermoelectric Ag-modified Bi0.5Sb1.5Te3 films on flexible substrates using a facile approach. Their optimized power factors are similar to 12.4 and similar to 14.0 mu W cm(-1) K-2 at 300 and 420 K, respectively. These high-power factors mainly originate from the optimized carrier transport of the composite system, through which a high level of electrical conductivity is achieved, whereas a remarkably improved Seebeck coefficient is simultaneously obtained. Bending tests demonstrate the excellent flexibility and mechanical durability of the composite films, and their power factors decrease by only about 10% after bending for 650 cycles with a bending radius of 5 mm. A flexible thermoelectric module is designed and constructed using the optimized composite films and displays a power density of similar to 1.4 mW cm(-2) at a relatively small Delta T of 60 K. This work demonstrates the potential of inorganic thermoelectric materials to be made on flexible/wearable substrates for energy harvesting and management devices.

采用超重力气液传质设备水力喷射空气旋流器(WSA)对乙苯模拟的VOC废水进行吹脱处理,考察了废水初始浓度、进口气速、射流流速、废水温度等因素对处理过程传质效率的影响.结果 表明,进口气速越大、废水温度越高,VOC吹脱去除传质效率越高;射流流速加大,VOC的吹脱处理效率先增大后保持不变;废水初始浓度对VOC的吹脱去除效率影响较小.初始浓度为45 mg/L的VOC废水,采用WSA吹脱处理3 min后,VOC的去除率可高达99％以上,气液传质效率是曝气柱等传统设备的2倍以上.

It is of great significance to understand the interactions between nanoparticles and polymers since they guide the development of tremendous applications, for example, in optoelectronic devices, biomedicine, and enhanced oil extraction. However, few studies have probed into this fundamental science as the emerging amphiphilic Janus nanosheets have a more complicated structure than homogeneous nanoparticles, which makes their interactions more complex. In this work, we try to understand the interactions between amphiphilic Janus nanosheets and a model nonionic polymer, hydroxyethyl cellulose (HEC), under different electrolyte and temperature conditions in both aqueous and biphasic systems by employing molecular dynamics simulations as well as experiments. It is found that the attachment of HEC onto the nanosheet surfaces exhibits ion-concentration-dependent behavior in the aqueous phase, helping to colloidally stabilize the nanosheets even in an environment with an extremely high salt concentration for a long duration. In the oil and water biphasic system, only elevated temperature promotes both Janus nanosheets and HEC to individually remain at the interface.

A universal and facile strategy has been developed to synthesize various porous metal nitrides for the hydrogen evolution reaction.

Because graphene oxide is so important for many applications and also the precursor for large quantity of graphene, a low cost and environmentally friendly method using much less acid is essential to the future of graphene oxide and graphene. It is a great challenge to reduce the acid usage to avoid the safety risk, but tremendous benefits could be achieved if this were made possible for the industrial-scale synthesis of graphene oxide and graphene. In this work, we report a fast and simple method that uses much less acid than the state of the art to obtain nanoscale graphene oxide by using the heat released by the reaction. With the introduction of dry ice, the reaction temperature can be well controlled, thus stabilizing the highly oxidative and explosive Mn2O7 intermediate in order to avoid safety risk.

We report a novel and scalable method to obtain amphiphilic Janus nanosheets in large quantities. By inducing electrostatic attraction using alkylamine with further tuned particle interactions, a highly stable water-in-oil high internal phase emulsion was generated while simultaneously performing single-side graphene oxide hydrophobization at the fluid interface.

Amorphous NiFe LDH nanosheets were decorated on nickel phosphide nanoarrays to form a 3D core–shell electrocatalyst for efficient water oxidation.

Developing efficient nonprecious electrocatalysts for hydrogen evolution reaction (HER) in alkaline media at large-current-density is appealing and challenging for large-scale water electrolysis. Here, we present a theoretical and experimental study to demonstrate that ternary Ni2(1-x)Mo2xP porous nanowire arrays grown on Ni foam, as a highly efficient and stable electrocatalyst toward alkaline HER under large-current-density. Density functional theory (DFT) calculations reveal that Mo substitution of Ni in Ni2P leads to optimal free energy of water activation and hydrogen adsorption on the catalyst surface. Benefiting from the enhanced intrinsic activity, large active surface area and fast gas releasing, the Ni2(1-x)Mo2xP catalyst exhibits an excellent HER activity with low overpotentials of 72, 240, and 294 mV at current densities of 10, 500, and 1000 mA cm(-2), respectively, along with superior stability in 1 M KOH. This highly active and stable catalyst enables an electrolyzer operating at 10 mA cm(-2) at a voltage of 1.51 V, 100 mA cm(-2) at 1.65 V, and 500 mA cm(-2) at 1.82 V in 1 M KOH at room temperature, which are much better than the benchmark of IrO2/Pt. Our 3D ternary Ni2(1-x)Mo2xP catalysts significantly advance the science and technology for commercial hydrogen production.