Conductive Polymer Intercalation Tunes Charge Transfer and Sorption-Desorption Properties of LDH Enabling Efficient Alkaline Water Oxidation.

Controlling and tuning surface properties of a catalyst have always been a prime challenge for efficient hydrogen production via water splitting. Here, we report a facile method for tuning both charger transfer and sorption-desorption properties of NiFe layered double hydroxide (LDH) by intercalating a conductive polymer of polypyrrole (ppy) via an interlayer confined polymerization synthesis (ICPS) process. Ex situ characterizations and in situ electrochemical quartz-crystal microbalance with dissipation (EQCM-D) tracking experiments showed that the intercalated ppy not only improved the charge transfer property of the resulting hybrid catalyst LDH-ppy but also made it more flexible and adaptive for quick and reversible sorption-desorption of reactants and intermediates during the oxygen evolution reaction (OER) process. Consequently, the as-prepared LDH-ppy exhibited a doubled catalytic current density over the bare LDH, as visualized by in situ scanning electrochemical microscopy (SECM) at the subnanometer scale. This work sheds light on orchestrating the charge and sorbate transfer abilities of catalysts for efficient water splitting by smartly combining inorganic and organic layers.

Unexpected high selectivity for acetate formation from CO2 reduction with copper based 2D hybrid catalysts at ultralow potentials.

Copper-based catalysts are efficient for CO2 reduction affording commodity chemicals. However, Cu(i) active species are easily reduced to Cu(0) during the CO2RR, leading to a rapid decay of catalytic performance. Herein, we report a hybrid-catalyst that firmly anchors 2D-Cu metallic dots on F-doped Cu x O nanoplates (Cu x OF), synthesized by electrochemical-transformation under the same conditions as the targeted CO2RR. The as-prepared Cu/Cu x OF hybrid showed unusual catalytic activity towards the CO2RR for CH3COO- generation, with a high FE of 27% at extremely low potentials. The combined experimental and theoretical results show that nanoscale hybridization engenders an effective s,p-d coupling in Cu/Cu x OF, raising the d-band center of Cu and thus enhancing electroactivity and selectivity for the acetate formation. This work highlights the use of electronic interactions to bias a hybrid catalyst towards a particular pathway, which is critical for tuning the activity and selectivity of copper-based catalysts for the CO2RR.

Measuring the Unmeasurable by IR Spectroscopy: Carbon Deposition Kinetics in Dry Reforming of Methane.

Dry reforming of methane converts two greenhouse gases to syngas, and Ni catalysts are commonly used for this reaction. A major catalyst deactivation mechanism is carbon deposition. Although numerous kinetic modelling works have been performed on carbon formation, there have been only scarce attempts to measure carbon deposition kinetics under relevant (but not real) conditions, owing to technical difficulties. Here, we report the first successful measurements of the kinetics under real reaction conditions. This was made possible by using a novel algorithm that we have developed. We use IR to measure the molar fractions of unreacted CH4 and CO2 , and reaction products, CO and H2 O, in the effluent from the reactor. By applying the general mass balance principle and the relevant reaction stoichiometries, the carbon deposition rate as well as the flow rates of all these gases in the effluent, including H2 , are calculated. Compared to the dominant GC-based approach for catalyst performance evaluation, this method has much higher time resolution and much smaller measurement errors.