Single-atom Mo-tailored high-entropy-alloy ultrathin nanosheets with intrinsic tensile strain enhance electrocatalysis.

The precise structural integration of single-atom and high-entropy-alloy features for energy electrocatalysis is highly appealing for energy conversion, yet remains a grand challenge. Herein, we report a class of single-atom Mo-tailored PdPtNiCuZn high-entropy-alloy nanosheets with dilute Pt-Pt ensembles and intrinsic tensile strain (Mo1-PdPtNiCuZn) as efficient electrocatalysts for enhancing the methanol oxidation reaction catalysis. The as-made Mo1-PdPtNiCuZn delivers an extraordinary mass activity of 24.55 A mgPt-1 and 11.62 A mgPd+Pt-1, along with impressive long-term durability. The planted oxophilic Mo single atoms as promoters modify the electronic structure of isolated Pt sites in the high-entropy-alloy host, suppressing the formation of CO adsorbates and steering the reaction towards the formate pathway. Meanwhile, Mo promoters and tensile strain synergistically optimize the adsorption behaviour of intermediates to achieve a more energetically favourable pathway and minimize the methanol oxidation reaction barrier. This work advances the design of atomically precise catalytic sites by creating a new paradigm of single atom-tailored high-entropy alloys, opening an encouraging pathway to the design of CO-tolerance electrocatalysts.

Preparation of a novel metal-free polypyrrole-red phosphorus adsorbent for efficient removal of Cr(VI) from aqueous solution.

The toxicity and carcinogenicity of Cr(VI) makes it a major threat to the health of animals and people. However, how to efficiently remove Cr(VI) still faces important challenges. In this study, a new metal-free polypyrrole-red phosphorus (PPy-RP) composite is successfully synthesized by in-situ oxidation polymerization for Cr(VI) removal from wastewater. The maximum adsorption capacity (qm) of Cr(VI) on PPy-RP-1 is 513.2 mg/g when the pH value is 2, which is far superior to RP nanosheets (207.8 mg/g) and PPy (294.9 mg/g). The improved qm can be ascribe to the good dispersion and increased specific surface area of PPy-RP adsorbent. Encouragingly, PPy-RP adsorbent still exhibits excellent stability after 7 cycles tests without a significant decline in removal efficiency, and remain above 81.4%. Based on the fittings of adsorption isotherms and kinetics, the process conforms to the pseudo-first-order kinetic model and the single-layer adsorption of the Langmuir model with an R2 value of 0.98533. The adsorption process is chemical and monolayer. The experimental result demonstrates that the PPy-RP can efficient removal Cr(VI) by electrostatic attraction and complexation reaction (formation of N-Cr(VI) bond) through the PPy on the surface. The results of this study indicate that PPy-RP is a promising adsorbent to remove the Cr(IV).

In-situ synthesis of dual Z-scheme heterojunctions of cuprous oxide/layered double hydroxides/nitrogen-rich graphitic carbon nitride for photocatalytic sterilization.

Two-dimensional (2D) layered double hydroxides (LDHs) and graphitic carbon nitride (g-C3N4) with sufficiently positive valence bands and negative conduction bands are promising materials for producing superoxide radicals (·O2-) and hydroxyl radicals (·OH) for photocatalytic sterilization; however, their relatively wide bandgaps limit the utilization of light in photocatalysis. Herein, the electronegative N-CN nanosheets were used to adsorb Cu2+, Zn2+ and Al3+ cations in situ to form uniformly distributed LDHs nanosheets. Then, the LDHs on LDHs/N-CN composites were partially reduced in situ into ultrafine Cu2O to harvest sufficient solar energy. Zeta potential measurements revealed that the constructed Cu2O/LDHs/N-CN composites and bacterial solution exhibited opposite charges, which induced strong electrostatic adsorption in photocatalytic sterilization. Under visible light, the highly hydrophilic 0D/2D/2D Cu2O/LDHs/N-CN heterojunctions exhibited the highest sterilization rate of 98.96% toward Escherichia coli without an obvious decrease after 4 cycles. It was experimentally and theoretically confirmed that a dual Z-scheme charge migration path in the Cu2O/LDHs/N-CN heterojunction was achieved, harnessing the full synergetic potential of the combined system. This work provides an effective method for synthesizing a robust, hydrophilic and positively charged heterojunction to further improve photocatalytic sterilization activity.