Exploration of efficient water oxidation catalysts (WOCs) is the primary challenge in conversion of renewable energy into fuels. Here we report a molecularly well-defined heterogeneous WOC with Aza-fused, π-conjugated, microporous polymer (Aza-CMP) coordinated single cobalt sites (Aza-CMP-Co). The single cobalt sites in Aza-CMP-Co exhibited superior activity under alkaline and near-neutral conditions. Moreover, the molecular nature of the isolated catalytic sites makes Aza-CMP-Co a reliable model for studying the heterogeneous water oxidation mechanism. By a combination of experimental and theoretical results, a pH-dependent nucleophilic attack pathway for O-O bond formation was proposed. Under alkaline conditions, the intramolecular hydroxyl nucleophilic attack (IHNA) process with which the adjacent -OH group nucleophilically attacks Co4+=O was identified as the rate-determining step. This process leads to lower activation energy and accelerated kinetics than those of the intermolecular water nucleophilic attack (WNA) pathway. This study provides significant insights into the crucial function of electrolyte pH in water oxidation catalysis and enhancement of water oxidation activity by regulation of the IHNA pathway.

capsulating the electrocatalysts. [27,[43][44][45][46] Recently, Zhao and coworkers [47] and Dai and co-workers [48,49] anchored Co, Ni-Fe based water splitting catalysts on multiwall carbon nanotubes (MWCNTs), these approaches not only enhanced the charge transportations but also increased the available catalytic sites. Although the obtained materials exhibit excellent activity toward water oxidation, the improvement are not significant compared to the original catalysts. Very recently, Zhao and co-workers [50] reported a metal free catalyst based on oxidized MWCNTs (O-MWCNTs) which shows comparable activities to the transition metal-based catalysts, due to the generated oxygen containing ketone groups on surface. This work inspired us to revisit the inorganic/nanocarbon hybrid materials in pursuit of more advanced OER electrocatalysts.As desired, a surprisingly high active OER catalyst has been obtained by simply anchoring the crystalline β−Ni(OH) 2 onto the O-MWCNTs. Different from previous studies, this is the first time that a hybrid material with low Ni contents exhibits extremely high activities for catalyzing oxygen evolution. [41,46] This work paves the path for designing new earth abundant material based alternatives to replace the benchmarking precious Ir/Ru OER catalysts.In order to densely embed the Nickel hydroxide on the MWCNT S , a two-step synthetic strategy was employed to synthesize the hybrid materials as shown in Figure 1. First, the as purchased MWCNTs were purified and mildly oxidized by a piranha solution followed by hydrothermal treatment according to the literature method. [50] Afterward, the freshly obtained O-MWCNTs were mixed with the hydrolysed Ni 2+ solution to afford the hybrid materials. NH 4 OH was introduced as the precipitating reactant instead of strong alkali solution to obtain a particularly pure nickel hydroxide. [51] To gain insights into how the Ni contents in the hybrid materials affect the efficiency toward catalytic water oxidation, five samples with various Ni contents were prepared following the same synthetic route (see the Supporting Information).To gain insight into the structure, morphologies, and composition of the synthesized materials, powder X-ray diffraction (PXRD), scanning electron microscopy, transmission electron microscopy (TEM), hard X-ray photoelectron spectroscopy measurements (HAXPES) and, thermogravimetry (TG) techniques were used to characterize these materials. The morphology of the O-MWCNTs was determined by TEM, as shown in Figure S2a in the Supporting Information. After the loading of Ni, PXRD, and HAXPES (Figure 2a and Figure 3) show that the obtained catalysts are composed of pure crystalline β-Ni(OH) 2 and O-MWCNTs, moreover, no metal impurities such as Fe and Co were detected ( Figure S1, SupportingThe rapid growth in energy demand, the continuous consumption of fossil fuels and the arising environmental concerns are stimulating significant research interests in developing alternative energy systems. [1] Production of hydrogen from electro...

According to the molecular structure design requirements of the fluid loss additive resistant to high temperature, 2‐acrylamide‐2‐methyl propane sulfonic acid (AMPS), acrylamide (AM), dimethyl diallyl ammonium chloride (DMDAAC) and sodium styrene sulfonate (SSS) are selected as the structure monomers. Using ammonium persulfate as initiator, a new quadripolymer is synthesized through free radical aqueous solution polymerization. According to the minimum filtration loss of the fresh water‐based drilling fluid with 0.5 wt % quadripolymer, The synthesis conditions are optimized by orthogonal test: the mole ratio of AMPS/AM/DMDAAC/SSS is 5/7/2/1, the monomer concentration is 30 wt %, the initiator concentration is 0.8 wt %, the reaction temperature is 75°C and the pH is 10. The structure of the quadripolymer is characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy. The results show that the quadripolymer contains all the designed functional groups. The thermal stability of the quadripolymer is tested by thermogravimetry, differential thermogravimetry, and differential scanning calorimetry. The results show that the thermal degradation of the quadripolymer is not obvious before 272.3°C. The rheological performance and filtration loss of the quadripolymer are evaluated. The results indicate that the filtration loss decreases with the increasing dosage of the quadripolymer before and after thermal aging test at 180°C for 16 h, and the filtration loss before the thermal aging test is smaller than that after the thermal aging test. The high temperature high pressure filtration loss (FL(HTHP)) experiment results also show that the quadripolymer fluid loss additive has excellent temperature‐resistant performance. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41762.

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Based on the mutual coupling effect among the compressor, the air cooler and pipes in the system of natural gas pipeline, innovatively with the goal of minimum energy consumption, this paper established a combined operation optimization model of the air cooler and compressor through the optimization of the switching scheme of compressors and air coolers, which can greatly reduce the production energy consumption of the pipeline system. Moreover, when the air temperature is taken as an optimization variable, the most proper temperature to start the air cooler of each compressor station can be worked out to guide the optimized operation of the pipeline, which is of high value for promotion and application. The case analysis of west-east natural gas pipeline II showed that among genetic algorithm (GA), particle swarm optimization (PSO), and simulated annealing (SA) algorithm that are used to solve the optimization model, the genetic algorithm is the fastest, and the simulated annealing algorithm the slowest, but the optimization results of the simulated annealing algorithm is the best, in which the reduced production energy consumption accounted for 33.77%, testifying the practicability and creativity of the optimization model. INDEX TERMS Natural gas pipeline, air cooler, compressor, operation optimization, algorithm.

There are many compressor stations along long-distance natural gas pipelines. Natural gas can be transported using different boot programs and import pressures, combined with temperature control parameters. Moreover, different transport methods have correspondingly different energy consumptions. At present, the operating parameters of many pipelines are determined empirically by dispatchers, resulting in high energy consumption. This practice does not abide by energy reduction policies. Therefore, based on a full understanding of the actual needs of pipeline companies, we introduce production unit consumption indicators to establish an objective function for achieving the goal of lowering energy consumption. By using a dynamic programming method for solving the model and preparing calculation software, we can ensure that the solution process is quick and efficient. Using established optimization methods, we analyzed the energy savings for the XQ gas pipeline. By optimizing the boot program, the import station pressure, and the temperature parameters, we achieved the optimal energy consumption. By comparison with the measured energy consumption, the pipeline now has the potential to reduce energy consumption by 11 to 16 percent.

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