Photoelectrodes and methods of making and use thereof

A method of making a photoelectrode, the method comprising:

• forming an insulator layer on a light absorbing layer, wherein the insulator layer has an average thickness of 20 nm or more;
• depositing a reactive layer comprising a reactive material on the insulator layer, such that the insulator layer is disposed between the light absorbing layer and the reactive layer, thereby forming a precursor electrode;
• annealing the precursor electrode such that the reactive material reacts with and diffuses through the insulator layer, thereby forming a set of spikes comprising the reactive material, wherein each of the set of spikes penetrates through the insulator layer to the light absorbing layer, such that each of the set of spikes is in physical and electrical contact with the light absorbing layer, thereby forming a spiked electrode;
• and
• subsequently depositing a catalyst material;
• thereby forming a photoelectrode comprising:
• the insulator layer disposed on the light absorbing layer,
• a set of protrusions that penetrates through the insulator layer to the light absorbing layer, such that each of the set of protrusions is in physical and electrical contact with the light absorbing layer, and
• a plurality of particles disposed on the insulator layer, wherein a least a portion of the plurality of particles are in physical and electrical contact with at least a portion of the set of protrusions,
• wherein the plurality of particles and optionally the set of protrusions comprise a catalyst material.