Modification of Carbon Nanotubes via Birch Reaction for Enhanced HER Catalyst by Constructing Pearl Necklace-Like NiCo2 P2 -CNT Composite.

Combining transition metal phosphides (TMPs) with carbon nanotubes (CNTs) is a promising and proven approach to enhance their performance in the electrochemical hydrogen evolution reaction (HER), due to the excellent conductivity and stability of CNTs. Generally, the deep oxidation of CNTs to form oxygen-containing groups on their surface is indispensable before combining them with TMPs. However, such approaches inevitably introduce a large number of defects to CNTs and apparently decrease their stability and electrical conductivity. Hence, fabricating TMP-CNT composites which does not come at the expense of CNTs' high electrical conductivity is quite desirable. In this work, alkylated CNTs (named as ACNT) functionalized via the Birch reaction are used to prepare the pearl necklace-like NiCo2 P2 -ACNT composites for electrocatalysts toward HER in acidic and alkaline conditions, respectively. The X-ray photoelectron spectroscopy, transmission electron microscope, and Fourier transform infrared spectroscopy characterizations indicate that the ACNTs are well modified with functional groups and keep their structural integrity, thereby maximizing their excellent conductivity. Compared to bare NiCo2 P2 and the NiCo2 P2 -CNT composites prepared with mildly oxidized CNTs and deeply oxidized CNTs, the NiCo2 P2 -ACNTs show far better HER performance and much faster kinetics.

Application of three tailing-based composites in treating comprehensive electroplating wastewater.

Heavy metals and chemical oxygen demand (COD) are major challenging pollutants for most electroplating wastewater treatment plants. A novel composite material, prepared with a mixture of calcium and sodium compounds and tailings, was simply mixed by ratios and used to treat a comprehensive electroplating wastewater with influent COD, total copper (T-Cu), and total nickel (T-Ni) respectively as 690, 4.01, and 20.60 mg/L on average. Operational parameters, i.e. the contact time, pH, mass ratio of calcium and sodium compounds and tailings, were optimized as 30 min, 10.0, and 4:2:1. Removal rates for COD, T-Cu, and T-Ni could reach 71.8, 90.5, and 98.1%, respectively. No significant effect of initial concentrations on removal of T-Cu and T-Ni was observed for the composite material. The adsorption of Cu(II) and Ni(II) on the material fitted Langmuir and Freundlich isotherms respectively. Weight of waste sludge from the calcium/sodium-tailing system after reaction was 10% less than that from the calcium-tailing system. The tailing-based composite is cost-effective in combating comprehensive electroplating pollution, which shows a possibility of applying the tailings in treating electroplating wastewater.

Hydrogenated borophene enabled synthesis of multielement intermetallic catalysts.

Supported metal catalysts often suffer from rapid degradation under harsh conditions due to material failure and weak metal-support interaction. Here we propose using reductive hydrogenated borophene to in-situ synthesize Pt/B/C catalysts with small sizes (~2.5 nm), high-density dispersion (up to 80 wt%Pt), and promising stability, originating from forming Pt-B bond which are theoretically ~5× stronger than Pt-C. Based on the Pt/B/C module, a series (~18 kinds) of carbon supported binary, ternary, quaternary, and quinary Pt intermetallic compound nanocatalysts with sub-4 nm size are synthesized. Thanks to the stable intermetallics and strong metal-support interaction, annealing at 1000 °C does not cause those nanoparticles sintering. They also show much improved activity and stability in electrocatalytic oxygen reduction reaction. Therefore, by introducing the boron chemistry, the hydrogenated borophene derived multielement catalysts enable the synergy of small size, high loading, stable anchoring, and flexible compositions, thus demonstrating high versatility toward efficient and durable catalysis.

Hydrogenated Boride-Assisted Gram-Scale Production of Platinum-Palladium Alloy Nanoparticles on Carbon Black for PEMFC Cathodes: A Study from a Practical Standpoint.

Platinum-palladium (PtPd) alloy catalysts with high durability are viable substituents to commercial Pt/C for proton exchange membrane fuel cells (PEMFCs). Herein, a facile approach for gram-scale preparation of PtxPd100-x alloy nanoparticles on carbon black is developed. The optimized Pt54Pd46/B-C catalyst shows a mass activity (MA) of 0.549 A mgPt-1 and a specific activity (SA) of 0.463 mA cm-2 at the rotating disk electrode (RDE) level, which are 3.4 and 1.9 times those of commercial Pt/C, respectively. In H2/O2 and H2/air PEMFCs, the membrane electrode assembly (MEA) with Pt54Pd46/B-C achieves peak power densities of 2.33 and 1.04 W cm-2, respectively, and shows negligible performance degradation after 100 h of running in H2/O2 conditions. Moreover, the MA of MEA with Pt54Pd46/B-C in H2/O2 PEMFC reaches 0.978 A mgPt+Pd-1 beyond the 2020 target of the Department of Energy (DOE) of 0.44 A mgPt-1. After 30k cyclic voltammetry cycles in PEMFC, the MA loss and cell voltage loss of MEA with Pt54Pd46/B-C are well within the DOE 2020 target. Density functional theory calculations reveal that the PtPd(111) surface can weaken the adsorption of *OOH and *OH compared to the Pt(111) surface, indicating that Pt54Pd46/B-C is more energetically favorable for the oxygen reduction reaction (ORR) than commercial Pt/C. This study offers a new approach for batch preparation of PtPd alloy-based catalysts for PEMFCs.