Porous materials are widely studied in many applications due to their high surface area and rich edge sites. Here, for the first time, we reported a simple and convenient method to synthesize porous nanosheets of metal hydroxides by selectively etching amphoteric Al in CoAl layered double hydroxides on carbon paper (CoAl-LDH/CP), and then convert them into porous cobalt phosphide nanosheets on carbon paper (p-CoP/CP) via low temperature phosphidation. In contrast to pristine cobalt phosphide nanosheets on carbon paper (CoP/CP), p-CoP/CP has lower overpotential, Tafel slope and charge transfer resistance as well as higher electrochemically active surface area. The excellent electrochemical characteristics make it have outstanding catalytic activity and stability over the whole pH range. In 1.0 M KOH, the p-CoP/CP only requires an overpotential of 57 mV to drive 10 mA cm. To achieve the same current density, it only needs overpotentials of 39 and 60 mV in 1.0 M HSO and 1.0 M PBS, respectively. To our knowledge, it is the best among those nonprecious electrocatalysts used for hydrogen evolution in neutral solution. Moreover, this catalyst offers good durability over the whole pH range.

Defect engineering and anionic regulation are effective approaches to improve the intrinsic activity of oxygen evolution reaction (OER) catalysts, particularly for highly efficient and low-cost cobalt-based electrocatalysts. Layered double hydroxides (LDHs) are considered as promising electrocatalysts toward OER. However, their electronic properties and active sites need to be optimized for their large-scale application. Herein, rapidly cationic defect and anion dual-regulated CoAl LDHs (PS-CoAl LDHs) were in situ synthesized in a few minutes via a modified water DBD plasma treatment. Abundant Al3+ vacancies and a relatively rough surface for S2- regulation were formed by the etching effect of the plasma. Consequently, the as-obtained PS-LDHs possess improved intrinsic conductivity and an optimal electronic structure. Simultaneously, the synergistic effect of the Al3+ vacancies and S2- regulation promote the exposure of active Co sites, resulting in an amorphous and porous surface for improving the OER performance.

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One-step, room-temperature etching and sulfuration of CoAl-LDH to form porous and amorphous CoSx(OH)y for superior oxygen evolution reaction.

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Biochar has good adsorption ability to various contaminants. In this work, peanut shell, corncob, cotton stalks, and crayfish shell were pyrolyzed under three temperatures (300, 450, 600 °C) to obtain biochars for the removal of Ni. The biochars were further modified with 2 mol/L NaS solution. Characterization results showed that the specific surface area and total pore volume of the modified biochars increased substantially. Among all the adsorbents, the modified corncob biochar (450 °C) showed the best Ni adsorption. The adsorption kinetics followed the Elovich model with an equilibrium time of 24 h. The maximum capacity of the modified biochar reached 15.40 mg/g. The adsorption process was affected by pH, temperature, and coexisting ions. Increasing pH (under 7) provided more adsorption sites which enhanced adsorption capacity. Experimental results also indicated that the main adsorption mechanism of Ni was ion exchange. Findings from this work suggest that modified biochar can be used as an effective adsorbent for the removal of Ni from wastewater. Graphical abstract ᅟ.

Interpolating precipitation data is of prime importance to hydrological design, modeling, and water resource management. Various models have been developed that estimate spatial precipitation patterns. The purpose of this study is to analyze different precipitation interpolation schemes at different time scales in order to improve the accuracy of discharge simulations. The study was carried out in the upstream area of the Changjiang River basin. The performance of all selected methods was assessed using cross-validation schemes, with the mixed methods ultimately displaying the best performance at all three time scales. However, the differences in performance between the spatial interpolation methods decreased with increasing time scales. The unifying catchment Soil and Water Assessment Tool (SWAT), ‘abcd’, and the Budyko equation were employed at the daily, monthly, and annual scales, respectively, to simulate discharge. The performance of the discharge simulation at the monthly and annual time scales was consistent with their ranks of spatial precipitation estimation. For coarse, or long period, precipitation, there were no significant differences. However, the mixed methods performed better than the single model for the daily, or short, time scale with respect to the accuracy of the discharge simulation.

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