Given the following free energy diagram for oxygen evolution reaction a 6 b 0.0 5 Ideal OER catalyst O2(g) Real OER catalyst RuO Iro, -0.5 PtO AG/EV + 3 2 HOOT U=0 -1.0 Mn,O, .46 TIO 4- MnO, -1.5 SnO 1 HO* *+2H20(1) Reaction coordinates -2.0 Vo -2.5 -1 0 1 2 3 4 AG-AG/ev HO a) Write the reaction equations for the four-electron pathway. It is required to label clearly all the intermediates, free sites, protons and electrons involved. [5 Marks] b) From the free energy diagram in Figure Q4 a, explain what the requirements for an ideal oxygen evolution reaction catalyst are. [5 Marks] c) Considering the scaling relationships between the binding energies of different intermediate species on catalyst surfaces, explain how the volcano shape in Figure Q4 b is plotted. [5 Marks] d) Explain why VO2 and SnO2 have lowest catalytic activities towards oxygen evolution reaction. [5 Marks] e) Explain whether IrO2 or RuO2 are most stable and elaborate why. [5 Marks]