A circuit based on the current feedback operational amplifier was constructed to accomplish on-line ohmic drop compensation in ultrafast cyclic voltammetry. Firstly, its characteristics were confirmed experimentally o...A circuit based on the current feedback operational amplifier was constructed to accomplish on-line ohmic drop compensation in ultrafast cyclic voltammetry. Firstly, its characteristics were confirmed experimentally on dummy cells. Then the reduction of anthracene in acetonitrile, a classical test example with very fast electron-transfer kinet-ics, was examined to prove them too. The results showed that this circuit could afford excellent ohmic drop com-pensation so that the undistorted voltammograms up to 2.2 MVs-1 scan rate can be recorded, and 2.5 MVs-1 if 5% error is tolerated.展开更多
Experimental technique has been inadequate to anodic overvoltage measurements in aluminum electrolysis. To determine its ohmic/voltage drop precisely, a current interruption technique was modified with a high frequenc...Experimental technique has been inadequate to anodic overvoltage measurements in aluminum electrolysis. To determine its ohmic/voltage drop precisely, a current interruption technique was modified with a high frequency digital oscilloscope, current interrupters with fast switching time, an improved cell configuration and a simulation applied to the oscillating potential decay curve. The results show that the technique can give good reproducibility for overvoltage studies. A substantial increase of anodic overvoltage is observed with graphite powder addition, metallic aluminum addition and CO bubbling in the melts.展开更多
A GaN vertical light emitting diode（LED）with a current block layer（CBL）was investigated.Vertical LEDs without a CBL,with a non-ohmic contact CBL and with a silicon dioxide CBL were fabricated.Optical and electrica...A GaN vertical light emitting diode（LED）with a current block layer（CBL）was investigated.Vertical LEDs without a CBL,with a non-ohmic contact CBL and with a silicon dioxide CBL were fabricated.Optical and electrical tests were carried out.The results show that the light output power of vertical LEDs with a non-ohmic contact CBL and with a silicon dioxide CBL are 40.6%and 60.7%higher than that of vertical LEDs without a CBL at 350 mA,respectively.The efficiencies of vertical LEDs without a CBL,with a non-ohmic contact CBL and with a silicon dioxide CBL drop to 72%,78%and 85.5%of their maximum efficiency at 350 mA,respectively. Moreover,vertical LEDs with a non-ohmic contact CBL have relatively superior anti-electrostatic ability.展开更多
基金the National Natural Science Foundation of China (No. 20173054).
文摘A circuit based on the current feedback operational amplifier was constructed to accomplish on-line ohmic drop compensation in ultrafast cyclic voltammetry. Firstly, its characteristics were confirmed experimentally on dummy cells. Then the reduction of anthracene in acetonitrile, a classical test example with very fast electron-transfer kinet-ics, was examined to prove them too. The results showed that this circuit could afford excellent ohmic drop com-pensation so that the undistorted voltammograms up to 2.2 MVs-1 scan rate can be recorded, and 2.5 MVs-1 if 5% error is tolerated.
文摘Experimental technique has been inadequate to anodic overvoltage measurements in aluminum electrolysis. To determine its ohmic/voltage drop precisely, a current interruption technique was modified with a high frequency digital oscilloscope, current interrupters with fast switching time, an improved cell configuration and a simulation applied to the oscillating potential decay curve. The results show that the technique can give good reproducibility for overvoltage studies. A substantial increase of anodic overvoltage is observed with graphite powder addition, metallic aluminum addition and CO bubbling in the melts.
基金Project supported by the National High Technology Research and Development Program of China(No2008AA03A197)the Knowledge Innovation Program of ISCAS(No08S4060000)
文摘A GaN vertical light emitting diode（LED）with a current block layer（CBL）was investigated.Vertical LEDs without a CBL,with a non-ohmic contact CBL and with a silicon dioxide CBL were fabricated.Optical and electrical tests were carried out.The results show that the light output power of vertical LEDs with a non-ohmic contact CBL and with a silicon dioxide CBL are 40.6%and 60.7%higher than that of vertical LEDs without a CBL at 350 mA,respectively.The efficiencies of vertical LEDs without a CBL,with a non-ohmic contact CBL and with a silicon dioxide CBL drop to 72%,78%and 85.5%of their maximum efficiency at 350 mA,respectively. Moreover,vertical LEDs with a non-ohmic contact CBL have relatively superior anti-electrostatic ability.
