Fine-tuning electronic structure of N-doped graphitic carbon-supported Co-and Fe-incorporated Mo_(2)C to achieve ultrahigh electrochemical water oxidation activity

Mo_(2)C is an excellent electrocatalyst for hydrogen evolution reaction(HER).However,Mo_(2)C is a poor electrocatalyst for oxygen evolution reaction(OER).Herein,two different elements,namely Co and Fe,are incorporated in Mo_(2)C that,therefore,has a finely tuned electronic structure,which is not achievable by incorporation of any one of the metals.Consequently,the resulting electrocatalyst Co_(0.8)Fe_(0.2)-Mo_(2)C-80 displayed excellent OER catalytic performance,which is evidenced by a low overpotential of 214.0(and 246.5)mV to attain a current density of 10(and 50)mA cm^(-2),an ultralow Tafel slope of 38.4 mV dec^(-1),and longterm stability in alkaline medium.Theoretical data demonstrates that Co_(0.8)Fe_(0.2)-Mo_(2)C-80 requires the lowest overpotential(1.00 V)for OER and Co centers to be the active sites.The ultrahigh catalytic performance of the electrocatalyst is attributed to the excellent intrinsic catalytic activity due to high Brunauer-Emmett-Teller specific surface area,large electrochemically active surface area,small Tafel slope,and low chargetransfer resistance.

Automated Multi-Meter Method for the Scaling of Low AC Voltage from 200 mV to 2 mV

A set of seven single junction thermal converter Micropotentiometers (μPots) has been constructed at the National Institute for Standards (NIS), Egypt. This set has been built to cover the low ac voltage ranges from 2 mV to 200 mV at frequencies from 40 Hz up to 20 kHz. The construction of the μPots set has been presented and an adopted calibration method has been performed as well. This method has been performed by means of a step-down procedure using a Digital Multi-Meter (DMM). The scaling procedures have been carried out in sequential steps starting from the calibration of the 200 mV-μpot by using DMM that is accurately calibrated at its 200 mV ac voltage range down to 2 mV-μPot. Furthermore, a new automatic calibration system has been established to achieve the scaling procedures. This system has been specially designed using Laboratory Virtual Instrument Engineering Workbench (LabVIEW) software to overcome the deficiencies of manual methods. The automatic calibration has been investigated of all mPots at different frequencies. The ac-dc differences for the μPots and their uncertainty evaluation from 2 mV to 200 mV at different frequencies from 40 Hz to 20 kHz have been determined.

Comparison of Minerogenic Conditions in Jiawula Multimetal Deposit in China with Uran Multimetal Deposit in Mongolia

The paper expounds the metallogenic characterist ic s of Jiawula multimetals deposit in China and Uran multimetals deposit in Mongol ia. Comparative study shows that both deposits are volcanic hydrothermal mineral ization with same epoch(Mesozoic), same source, same temperature, and same miner al assemblage, but volcanic structure are different. Therefore, both deposits ca n draw on experience of each other and supplement in future of second time ore- prospecting, and point out the new direction of ore-prospecting.

Synergistic coupling of Ni_(3)ZnC_(0.7)decorated with homogeneous multimetal CoNiCuFe nitrogen-codoped carbon matrix as high-entropy catalysts for efficient overall water splitting

Due to unique electrical properties and high catalytic efficiency,transition metal nitrogen-codoped car-bide(TM-N-C)has attracted tremendous interest as a multifunctional electrocatalyst for water splitting.Unlike traditional single-source modification,herein a novel pomegranate-like high-entropy(HE)elec-trocatalyst of Ni_(3)ZnC_(0.7)decorated with homogeneous multimetal(Fe,Co,Cu,and Ni)nitrogen-codoped carbon matrix(Ni_(3)ZnC_(0.7)@CoNiCuFe-NC)is reported.It can be implemented by the simple thermal an-nealing method of multimetal codoped zeolitic imidazolate framework(ZIF).Benefiting from the syn-ergistic effects of plentiful TM-N-C species,template effect of ZIF and distinct nanoporous structure,HE electrocatalyst Ni_(3)ZnC_(0.7)@CoNiCuFe-NC exhibits outstanding electrocatalytic performance.When ap-plied in strong alkaline electrolyte(1.0 M KOH),the overpotentials of Ni_(3)ZnC_(0.7)@CoNiCuFe-NC present as low as 202 and 97 mV for oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)at 10 mA cm^(−2)current density.Surprisingly as a bifunctional electrode,it can achieve the low cell voltage of 1.53 V at 10 mA cm^(−2)current density for overall water splitting,which is comparable to conventional IrO_(2)||Pt/C electrode and superior to the recently reported analogous bifunctional catalysts.Thus,the work proposes the direction for the rational design of homogeneous distribution of TM-N-C material for water splitting in the green hydrogen energy industry.