Magnetically modified semiconductor electrodes for photovoltaics, photoelectrosynthesis, and photocatalysis

Abstract

A device for hydrogen gas production comprising a working electrode comprising a magnetically-modified semiconductor electrode. Onset of hydrogen gas evolution for the device, measured at a current density of about 0.4 mA/cm 2 , occurs at an overpotential of no more than about −1200 mV, or no more than about −600 mV, or no more than about −500 mV. The magnetically-modified semiconductor working electrode provides the device with a photoconversion efficiency of at least about 0.1%, or at least about 1.6%, or at least about 6.2%. Other applications include photovoltaics, photoelectrochemical synthesis, and photocatalysis.

1 . A device for production of hydrogen gas comprising:
 at least one working electrode, wherein the working electrode comprises at least one magnetically-modified semiconductor electrode; and   at least one counter electrode,   wherein the onset of hydrogen gas evolution for the device, measured at a current density of about 0.4 mA/cm 2 , occurs at an overpotential of no more than about −1200 mV.   
     
     
         2 . The device of  claim 1 , wherein the working electrode comprises p-type silicon with a low doping level. 
     
     
         3 . The device of  claim 1 , wherein the working electrode comprises p-type silicon having resistivity of about 0.01 to about 10 Ω-cm. 
     
     
         4 . The device of  claim 1 , wherein the working electrode comprises p-type silicon comprising a surface orientation comprising <100>, <110>, or <111>. 
     
     
         5 . The device of  claim 1 , wherein the working electrode comprises silane-coated magnetite. 
     
     
         6 . The device of  claim 1 , wherein the working electrode comprises a polymeric material. 
     
     
         7 . The device of  claim 1 , wherein the counter electrode comprises platinum. 
     
     
         8 . The device of  claim 1 , further comprising an electrolyte. 
     
     
         9 . The device of  claim 1 , further comprising Ga—In eutectic or silver epoxy. 
     
     
         10 . The device of  claim 1 , wherein the onset of hydrogen gas evolution occurs at an overpotential of no more than about −600 mV. 
     
     
         11 . The device of  claim 1 , wherein the onset of hydrogen gas evolution occurs at an overpotential of no more than about −500 mV. 
     
     
         12 . A device for production of hydrogen gas comprising:
 at least one working electrode, wherein the working electrode comprises a p-type semiconductor, a magnetic material, and an ion-exchange polymer, wherein the magnetic material and the ion-exchange polymer are disposed on the p-type semiconductor; and   at least one counter electrode.   
     
     
         13 . The device of  claim 12 , wherein the p-type semiconductor comprises silicon with a low doping level. 
     
     
         14 . The device of  claim 12 , wherein the p-type semiconductor has resistivity of about 0.01 to about 10 Ω-cm. 
     
     
         15 . The device of  claim 12 , wherein the working electrode comprises p-type silicon comprising a surface orientation comprising <100>, <110>, or <111>. 
     
     
         16 . The device of  claim 12 , wherein the magnetic material comprises silane-coated magnetite. 
     
     
         17 . The device of  claim 12 , wherein the ion-exchange polymer comprises NAFION™. 
     
     
         18 . The device of  claim 12 , wherein the counter electrode comprises platinum mesh. 
     
     
         19 . The device of  claim 12 , further comprising an electrolyte. 
     
     
         20 . The device of  claim 12 , further comprising Ga—In eutectic or silver epoxy. 
     
     
         21 . The device of  claim 12 , wherein the working electrode and counter electrode provide the device with a photoconversion efficiency of at least about 0.1%. 
     
     
         22 . The device of  claim 21 , wherein the wherein the magnetic material and the ion-exchange polymer are disposed on less than the entire surface of the p-type semiconductor. 
     
     
         23 . The device of  claim 21 , wherein the photoconversion efficiency is at least about 1.6%. 
     
     
         24 . The device of  claim 21 , wherein the photoconverision efficiency is at least about 6.2%. 
     
     
         25 . A device for production of hydrogen gas comprising:
 at least one working electrode, wherein the working electrode comprises a magnetically-modified semiconductor electrode; and   at least one counter electrode,   wherein the working electrode and counterelectrode provide the device with a photoconversion efficiency of at least about 0.1%.   
     
     
         26 . The device of  claim 25 , wherein the working electrode comprises p-type silicon with a low doping level. 
     
     
         27 . The device of  claim 25 , wherein the working electrode comprises p-type silicon having resistivity of about 0.01 to about 10 Ω-cm. 
     
     
         28 . The device of  claim 25 , wherein the working electrode comprises p-type silicon comprising a surface orientation comprising <100>, <110>, or <111>. 
     
     
         29 . The device of  claim 25 , wherein the working electrode comprises silane-coated magnetite. 
     
     
         30 . The device of  claim 25 , wherein the working electrode comprises a polymeric material. 
     
     
         31 . The device of  claim 25 , wherein the counter electrode comprises platinum. 
     
     
         32 . The device of  claim 25 , further comprising an electrolyte. 
     
     
         33 . The device of  claim 25 , further comprising Ga—In eutectic or silver epoxy. 
     
     
         34 . The device of  claim 25 , wherein the photoconversion efficiency is at least about 1.6%. 
     
     
         35 . The device of  claim 25 , wherein the photoconversion efficiency is at least about 6.2%. 
     
     
         36 . A method of producing hydrogen gas, comprising:
 providing the device of  claim 1 ; and   producing hydrogen gas using the device, wherein the onset of hydrogen gas evolution for the device, measured at a current density of about 0.4 mA/cm 2 , occurs at an overpotential of no more than about −1200 mV.   
     
     
         37 . The method of  claim 36 , wherein the onset of hydrogen gas evolution occurs at an overpotential of no more than about −600 mV. 
     
     
         38 . The method of  claim 36 , wherein the onset of hydrogen gas evolution occurs at an overpotential of no more than about −500 mV. 
     
     
         39 . A method of producing hydrogen gas, comprising:
 providing the device of  claim 25 ; and   producing hydrogen gas using the device, wherein the photoconversion efficiency is at least about 0.1%.   
     
     
         40 . The method of  claim 39 , wherein the photoconversion efficiency is at least about 1.6%. 
     
     
         41 . The method of  claim 39 , wherein the photoconversion efficiency is at least about 6.2%. 
     
     
         42 . A method of producing hydrogen gas, comprising:
 providing the device of  claim 12 ; and   producing hydrogen gas using the device.   
     
     
         43 . The method of  claim 42 , wherein hydrogen gas is produced upon exposure of the device to photons. 
     
     
         44 . The method of  claim 42 , wherein the working electrode comprises p-type silicon with a low doping level, resistivity of about 1 to about 10 Ω-cm, surface orientation comprising <100>, <110>, or <111>; wherein the magnetic material comprises silane-coated magnetite;
 wherein the ion-exchange polymer comprises NAFION™; and wherein the wherein the magnetic material and the ion-exchange polymer are disposed on less than the entire surface of the p-type semiconductor. 
 
     
     
         45 . A device for production of hydrogen gas comprising:
 at least one working electrode, wherein the working electrode comprises p-type silicon with a low doping level, resistivity of about 1 to about 10 Ω-cm, and surface orientation comprising <100>, <110>, or <111>; silane-coated magnetite; and ion-exchange polymer, wherein the magnetite and the ion-exchange polymer are disposed on the p-type semiconductor; and   at least one counter electrode, wherein the counter electrode comprises platinum mesh;   wherein the working electrode and counter electrode provide the device with a photoconversion efficiency of at least about 1.6%, and   wherein the onset of hydrogen gas evolution for the device, measured at a current density of about 0.4 mA/cm 2 , occurs at an overpotential of no more than about −600 mV.