But then it will end up in the atmosphere again shortly after. I think the idea is to achieve a reduction in CO2. However, is there a process that sucks out CO2 more effectively than trees doing photosynthesis?
None are at scale yet. There is a lot of hand wringing about the cost (negligible compared to annoying Putin or OPEC), and some moral arguments from the greens about how it is unethical to expect our kids to spend electricity to clean up our mess (even though the cost of electricity production is currently dropping faster than it has in our lifetimes).
Yes, you absolutely can trap much more CO2 per unit of collection area with photovoltaics than trees can manage. The trees are cheaper per unit of carbon capturing capacity, but what they bind the carbon into is less useful.
That said, wood can be burned in such a way that only the hydrogen oxidizes, leaving charcoal that, powdered, can massively improve soil quality particularly in rainforests. Up until 500 years ago there was a thousands-of-years-long project doing this in the Amazon, interrupted by plague and collapse.