It's extremely easy to beat the efficiency of photosynthesis since plants are so inefficient. The highest estimate I have seen for carbon sequestration by trees is 7 tons of CO2 per acre, which doesn't include losses from converting wood to biochar for long term carbon capture. Direct air capture of CO2 requires about 2000 KWh per ton of CO2. An acre of solar panels produces an average of 357000 KWh of electricity per year. That means that direct air capture is at least 25x more efficient at converting solar energy to captured CO2. That efficiency is important considering the scale at which we will need to sequester carbon in the next few decades. Cost efficiency is a different matter, but even then I believe direct air capture will beat biochar very soon if it hasn't already.
Why we are blindly fixated at CO2 only?
The artificial cure may be worse than disease. Plants sequester other substances and retain water, regulate temperatures and is home to biodiversity. With artificial solution we will endup with dead deserts of hard to recycle hardware. Nature did it better for millions of years.
Bio-solutions will definitely make up the future of carbon removal but while nature was able to keep itself in equilibrium for millions of years a few centuries of human behaviour has thrown it out of balance. Humans will need to undo their own damage _and_ restore nature.
Until carbon sequestration can make bricks or another useful material as a carbon sink, it'll sit as a niche own used for virtue signaling by politicians rather than actual change that moves the meter.
Not even bricks as by time they will become garbage and yet another recycling issue. We would need to dump it back deep underground into mineshafts and oil wells.
