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Replacing Pt-based catalysts with cost-effective, highly efficient, and durable platinum group metal-free catalysts for oxygen reduction reaction (ORR) is crucial for commercializing hydrogen fuel cells. Herein, we present a highly...

We have studied two structurally related, water‐insoluble ruthenium complexes [RuII(tpy*)(phenCO2)](PF6) (1) (tpy*=5,4′,5′′‐tri‐tert‐butyl‐2,2′;6′,2′′‐terpyridine; phenCO2H=1,10‐phenanthroline‐2‐carboxylic acid) and [RuII(tpy)(dmphen)(Cl)](PF6) (2) (tpy=2,2′;6′,2′′‐terpyridine; dmphen=2,9‐dimethyl‐1,10‐phenanthroline, also known as neocuproine) and their electrocatalytic activity for CO2 reduction in acetonitrile and after immobilization on the reduced graphene oxide (rGO) in water (pH 7.2). Under homogeneous conditions (in CO2 saturated acetonitrile solution), characteristic major CO2 reduction waves indicate ∼280 mV lower overpotential upon changing the catalyst from 1 to 2. The higher CO2 electroreduction performance of 2 is also reflected on the heterogeneous rGO surfaces.

Combining the advantages of homogeneous and heterogeneous catalytic systems has emerged as a promising strategy for electrochemical CO 2 reduction although developing robust, active, product-selective, and easily available, catalysts remains a major challenge. Herein, we report the electroreduction of CO 2 catalyzed by cobalt and benzimidazole containing Vitamin B 12 immobilized on the surface of reduced graphene oxide (rGO). This hybrid system with a naturally abundant molecular catalyst produces CO with high selectivity and a constant current density in an aqueous buffer solution (pH 7.2) for over 10 h. A Faradaic efficiency (FE) of 94.5% was obtained for converting CO 2 to CO at an overpotential of 690 mV with a CO partial current density (j CO ) of 6.24 mA cm −2 and a turnover frequency (TOF) of up to 28.6 s −1 . A higher j CO (13.6 mA cm −2 ) and TOF (52.4 s −1 ) can be achieved with this system at a higher overpotential (790 mV) without affecting the product selectivity (∼94%) for CO formation. Our experimental findings are corroborated with density functional theory (DFT) studies to understand the influence of the covalently attached and redox-active benzimidazole unit. To the best of our knowledge, this is the first example of naturally abundant vitamin being immobilized on a conductive surface for highly efficient CO 2 electroreduction.

This paper focusses on the effect of thermal ageing and mechanical properties of empty fruit bunch filled polyvinyl alcohol composites. A composite plate with various volume fractions from 0·5 to 3 wt-% of empty fruit bunch was fabricated. The composites were created by a casting evaporation technique. Generally, there appears to be intimate contact between empty fruit bunch fibre and polyvinyl alcohol. In composites with higher fibre content, there is a greater tendency for filler interaction to take place. The results showed that the addition of 1 wt-% of empty fruit bunch fibre increased the tensile strength and modulus of the polyvinyl alcohol/ empty fruit bunch fibre composite. There was a further increase in the mechanical properties of all the samples after thermal ageing at 50°C for 6 hours.