Electrochemical Evolution of Ru-Based Polyoxometalates into Si,W-Codoped RuOx for Acidic Overall Water Splitting.

Despite intensive studies over decades, the development of electrocatalysts for acidic water splitting still relies on platinum group metals, especially Pt and Ir, which are scarce, expensive, and poorly sustainable. Because such problems can be alleviated, Ru-based bifunctional catalysts such as rutile RuO2 have recently emerged. However, RuO2 has a relatively low activity for hydrogen evolution reactions (HER) and low stability for oxygen evolution reactions (OER) under acidic conditions. In this study, the synthesis of a RuOx -based bifunctional catalyst (RuSiW) for acidic water splitting via the electrochemical evolution from Ru-based polyoxometalates at cathodic potentials is reported. RuSiW consists of the nanocrystalline RuO2 core and Si,W-codoped RuOx shell. RuSiW exhibits outstanding HER and OER activity comparable to Pt/C and RuO2 , respectively, with high stability. Computational analysis suggests that the codoping of RuOx with W and Si synergistically improves the HER activity of otherwise poor RuO2 by shifting the d-band center and optimizing atomic configurations beneficial for proper hydrogen adsorption. This study provides insights into the design and synthesis of unprecedented bifunctional electrocatalysts using catalytically inactive and less explored elements, such as Si and W.

Ultrafast and on-demand oil/water separation with vertically aligned cellulosic smart sponge.

Slow oil sorption speed of commercial non-woven polypropylene (PP) sorbent remains a major challenge for efficient clean-up of oil spillage. Adsorption-based polymeric sponge oil removing offers an appealing way to solve this challenge by increasing surface area. However, the tortuous oil sorption path and plastic waste after oil uptake are two long-standing bottlenecks for realizing efficient oil spill removal. Here, we report a vertically aligned-biomass fiber junctioned sorbents (a-BFJS), by confining delignified biomass with carbon nanotube (CNT), polyvinyl alcohol (PVA), and methyltrimethoxysilane (MTMS). The sorbent shows an excellent performance towards xylene sorption capacity with uptake about 50 g g-1 within 10 s. This is due to the wide and short pathway of their aligned channels, which improves the capillary effect and fast oil transport in the oriented channels. Moreover, the sponge exhibits fast oil sorption-desorption kinetics enabled by simple mechanical squeezing. We further engineered a scalable rapid continuous oil skimming with simple peristaltic pump. The oil recovering using a-BFJS realized high oil selectivity from xylene/water emulsion. Our demonstration of the high-performance aligned channel sorbent and scalable oil removing sponge offers an eco-friendly and promising strategy for efficiently removing oil from oil spills from water.

Highly efficient and recyclable polyolefin-based magnetic sorbent for oils and organic solvents spill cleanup.

The oil dispersants have been applied in a broad oil pollution area, but the dispersed oil caused environmental problems during sedimentation. Unlike oil dispersants, flake type polyolefin-based oil absorbent (PA) is not emulsified and shows excellent swelling characteristic for oil removal. However, the sprayed PA flakes cannot be fully collected due to its tiny architectures, the uncollected flakes can cause unintentional secondary pollution. In this study, we develop a kind of flake type polyolefin-based magnetic absorbent (PMA) hybridized with magnetic nanoparticle, to facilitate the collection process. The magnetic nanoparticle is uniformly dispersed in PMA due to the hydrophobic functionalization of iron oxide nanoparticle. This enables the convenient collection of isolated sorbent flakes even when they were placed in the marine system and show a desirable oil recovery performance up to about 37 times for organic solvent. Moreover, oil-soaked PMA flakes can be fully converted into refined oil via a pyrolysis process. After pyrolysis, the thermally undecomposed compounds, which comprise of carbon residue and magnetic nanoparticle, can be also separated by a magnet. The as-prepared flake type PMA possesses good oil recovery performance, fast magnetic response, and efficient oil recycling, thus representing an environmentally promising method for oil spill cleanup.