SHE. A platinum electrode that runs the half reaction 2 H+(aq, 1M) + 2 e- H2(g, 1 atm), chosen as a reference for cell voltages. The electrode potential of the standard hydrogen electrode is defined to be zero volts.
The standard hydrogen electrode (abbreviated SHE), also called normal hydrogen electrode (NHE), is a redox electrode which is placed in the basis of the thermodynamic scale of oxidation-reduction potentials. Its absolute electrode potential is estimated to be 4.4V to 4.6V, but to form a basis for comparison with all other electrode reactions, Hydrogen's standard electrode potential (E0) is declared to be zero. Potentials of any other electrodes are compared with the standard hydrogen electrode.