Third Generation PV and Other Ways to Utilize Solar Energy Solar - PowerPoint PPT Presentation

Third Generation PV and Other Ways to Utilize Solar Energy Solar Fuels Week 6.3 Arno Smets, Wilson Smith, Paula Perez Rodriguez

Electricity Heat Solar Fuels

Ragone Plot: Energy vs Power Density Fuel Energy Energy [kJ/g] [kJ/l] Coal 29.3 - Wood 14.6 - Gasoline 43.5 30590 Diesel 42.7 29890 Natural Gas 50.02 31.7 Hydrogen 119.9 10 Source : “ Indication of anomalous heat energy production in a reactor device containing loaded nickel powder ”. Levi et al. 2013

Can we learn from Nature?

Energy H 2 O Hydrogen cycle Energy Electrolysis Energy H 2 CO 2 Water Gas Shift Combustion CH 4 O 2 CO Fisher-Tropsh Energy

Direct photoelectrolysis 2H + +2e -  H 2 Cathodic: Anodic: 2H 2 O  O 2 +4H + +4e - TOTAL: H 2 O  H 2 + ½ O 2 Potential: 1.23 V

Band bending P-type semiconductor: Cathode N-type semiconductor: Anode

Challenges for photoelectrochemistry 2 3 1. Absorption 2. Separation of charges 1 3. Catalysis 3

Materials for photoelectrodes

Improving photoelectrode efficiency 4 4 4 BiVO 4 BiVO 4 BiVO 4 +Gradient doped + Catalyst + Catalyst 2 ) 2 ) 2 ) +Catalyst j (mA/cm j (mA/cm j (mA/cm 2 2 2 BiVO 4 BiVO 4 BiVO 4 dark dark dark 0 0 0 0.5 0.5 0.5 1.0 1.0 1.0 1.5 1.5 1.5 2.0 2.0 2.0 V vs. RHE (V) V vs. RHE (V) V vs. RHE (V)

Potential of the reaction Overpotential Solar cell 0.8V Needed voltage 1.5V for the reaction to happen Reaction potential Photoelectrode 1.23V 0.6V

Hybrid photoelectrode Counter Photoelectrode electrode Solar cell

Hybrid photoelectrode J sc J sc Solar cell J photo Current Current 𝜃 𝑇𝑈𝐼 = 𝐾 𝑞ℎ𝑝𝑢𝑝 ⋅ 1.23𝑊 𝑄 Photoanode 0 V operational Potential Potential V oc V oc

MECS PV-PEC Device 4.9% Solar to Hydrogen Conversion Efficiency!

Thank you for your attention!