The high cost and impurity tolerance of Pt-group metal electrocatalysts used for HER and OER are significant challenges to overcome in order to achieve wide-spread electrolyzer use. Discovery of active, inexpensive, and impurity tolerant electrocatalysts should be guided by activity trends derived from density functional theory (DFT) calculations and experimental studies on well-characterized thin films. These trends then need to be extended to industrially relevant high surface area catalysts in order to bridge the materials gap.

In this talk we will use three examples to illustrate our efforts in reducing or replacing Pt-group metals for HER and OER. The first example is the utilization of monolayer (ML) Pt-group metals over transition metal carbide (TMC) substrates for HER in acid electrolyte. Metal-modified TMCs are promising inexpensive replacements for Pt-group metals because they have shown the ability to tune hydrogen binding energy, which is a descriptor for predicting the HER activity in acid. We will also use ML Pt-NbC thin films to compare the HER activity in acid and alkaline electrolytes, and to illustrate the impurity tolerance of Pt-NbC in the presence of tap water ions. The second example utilizes non-precious bimetallic catalysts for HER in alkaline electrolyte. The value of hydrogen binding energy appears to be a useful descriptor for predicting monometallic and bimetallic catalysts for HER in alkaline electrolyte. The last example shows the feasibility of coating monolayer coverages of IrO₂ on transition metal nitrides for OER in acid electrolyte. All three examples demonstrate the importance of correlating theoretical calculations with experimental measurements for identifying alternative electrocatalysts for water electrolysis.