Optimizing 3d spin polarization of CoOOH by in situ Mo doping for efficient oxygen evolution reaction

Transition-metal oxyhydroxides are attractive catalysts for oxygen evolution reactions(OERs).Further studies for developing transition-metal oxyhydroxide catalysts and understanding their catalytic mechanisms will benefit their quick transition to the next catalysts.Herein,Mo-doped CoOOH was designed as a high-performance model electrocatalyst with durability for 20 h at 10 mAcm−2.Additionally,it had an overpotential of 260 mV(glassy carbon)or 215 mV(nickel foam),which was 78 mV lower than that of IrO_(2)(338 mV).In situ,Raman spectroscopy revealed the transformation process of CoOOH.Calculations using the density functional theory showed that during OER,doped Mo increased the spin-up density of states and shrank the spin-down bandgap of the 3d orbits in the reconstructed CoOOH under the electrochemical activation process,which simultaneously optimized the adsorption and electron conduction of oxygen-related intermediates on Co sites and lowered the OER overpotentials.Our research provides new insights into the methodical planning of the creation of transition-metal oxyhydroxide OER catalysts.

Pre-combustion mercury removal with co-production of hydrogen via coal electrolysis

Pre-combustion mercury removal via coal electrolysis was performed and investigated on a bench-scale coal electrolytic cell(CEC)systemically,and factorial design was used to determine the effect of different operating conditions(coal particle size,operating temperature,operating cell voltage,and flow rate of slurry)on the percentage of mercury removal,percentage of ash removal,and dry heating value change.The results showed that the operating cell voltage,as well as the interaction between operating cell voltage and coal particle size,are significant factors in the percentage of mercury removal.There is no significant factor in the percentage of ash removal and the dry heating value change,but the coal could be purified while keeping the dry heating value almost constant after electrolysis.A co-product of hydrogen could be produced during coal electrolysis with 50%lower energy consumption compared with water electrolysis.Meanwhile,a mechanism for mercury removal in coal was proposed.The facts indicate that coal electrolysis is a promising method for precombustion mercury removal.

Demonstration of no catalytical activity of Fe-N-C and Nb-N-C electrocatalysts toward nitrogen reduction using in-line quantification

Ammonia(NH3)production via the electrochemical nitrogen reduction reaction(NRR)is a promising method for sustainable generation of this important chemical.Efforts are ongoing in finding an efficient,stable,and selective catalyst that will enable the reaction.However,progress is hindered in the field due to lack of reproducibility,most likely a consequence of reports of false-positive results due to improper measurement control and methods.In this study,we explore the NRR activity of a promising class of single atom catalysts,transition metal-nitrogen-carbon(M-N-C)electrocatalysts.Using a state-of-the-art in-line ammonia quantification methodology,with detection limit as low as 1 ppb for ammonia,we show that single atom Nb and Fe embedded in a stable carbon and nitrogen framework do not electrochemically reduce N_(2) to NH_(3).Critically,this demonstrates that our experimental setup with in-line sequential injection analysis successfully excludes ammonia contamination from the gas supply and atmospheric sources,allowing for thorough and high-throughput examination of potential NRR catalysts.