The first problem is that the dimension of your antenna, at 10nm, is much smaller than your wavelength of 800nm. Your antenna will have a simple dipole pattern, but a very low aperture area for energy capture. Such small antennas do have the advantage of having a very wide bandwidth, but it is never really economic to use an antenna less than a tenth of a wavelength across.
On the good side there is a warm glow. The wavelength of 800nm implies an IR photon with an energy of 1239.84 / 800 = 1.55 eV, just the sort of thing you need to charge a chemical cell to power an organic reaction.
qnach said:
4. intend to receive
5. ...presumably it will be coupled to space?...maybe a passive scatterer...
Well, to receive energy, the antenna must take photons from the passing flux and feed that energy into a transmission line for delivery to the client. The alternative is to put a rectifying detector at, or in the antenna, which might generate a 1.55 volt potential difference, but a very small current as electrons are pumped one by one along the charge conveyors.
Unfortunately, the undervalued common junkbox detectors available, P680 and P700, peak at a slightly higher energies than your longer wave 800nm.
See;
https://en.wikipedia.org/wiki/Photosystem_I#Antenna_complex
and;
https://en.wikipedia.org/wiki/Photosystem_II#Structure
Still, you may be able to hand craft a lower voltage detector, or maybe warm it up in the ocean to get the thermal broadening necessary for improved efficiency.
Also consider;
https://en.wikipedia.org/wiki/Optical_rectenna
I assume you realize that a multi-layer PV cell would be more efficient at energy production, but very poor at CO
2 sequestration.
