Lights on: When illuminated, p‐type Si nanowires donate photogenerated electrons to aromatic ketones, producing reactive radicals that can harvest CO2 to yield α‐hydroxy acids (see scheme). The reaction scheme closely resembles that of natural photosynthesis and gives up to 98 % yield and selectivity. Products obtained by this reaction include important precursors for nonsteroidal anti‐inflammatory drugs, such as ibuprofen and naproxen.