From Moldy Orange Waste to Natural Reductant and Catalyst Support: Active Palladium/Biomass‐Derived Carbonaceous Hybrids for Promoted Methanol Electro‐Oxidation

Abstract

Facile, green, and low-cost synthesis of advanced electrocatalysts is widely considered an urgent issue and a current challenge for clean energy conversion. Here, we report the green fabrication of a new Pd/C(OJ) hybrid, using orange juice (OJ) simultaneously as a natural reductant and a support precursor, for the methanol oxidation reaction (MOR) in alkaline media. The juice extracted from discarded moldy oranges is capable of reducing the [PdCl 4 ] 2À species into metallic Pd through a simple hydrothermal reaction, and then becomes the nitrogen-doped carbonaceous support after pyrolysis for active catalyst loading. In the synthesized Pd/C(OJ) hybrid, Pd nanoparticles with a mean size of 7.3 nm are highly dispersed throughout the support, providing a larger electrochemically active surface area than commercial Pd/C. As a result, the Pd/C (OJ) electrocatalyst exhibits 1.78 times the mass activity of the latter for the MOR. The preferable performance durability of Pd/ C(OJ) is also verified by using cyclic voltammetry and simulative startupÀshutdown measurements.

Preparation and Application of Biochar-Based Catalysts for Biofuel Production

“…For example, the pyrolysis of high-lignin biomass such as pine wood and spruce wood produces biochar with a high yield and a high fixed-carbon content [35]. It is easier for microcrystalline cellulose to produce biochar with graphitic structures at a relatively low temperature (e.g., 350 • C) than for lignocellulosic biomass [22]. (2) The Biomass Matrix For some biomasses, their microstructures are basically maintained over a pyrolysis process [14].…”

“…The processes for which biochar-based catalysts were tested include biomass refining [13,14,18], NO x removal [19,20], ammonia ozonation [21], electrocatalytic oxygen reduction and methanol oxidation in fuel cells [22,23], photocatalytic degradation of organics [24,25], nitrate degradation in wastewater [26], etc. A good review on the application of biochar-based catalysts was provided by Lee et al [11] and Xiong et al [14].…”