The phrase 'has been proved to be' is correct and can be used in written English. You can use it when you are trying to convey that something has been demonstrated or verified through evidence or some form of investigation. For example: "It has been proved to be true that humans evolved from primates."
PSO has been proved to be an effective optimization technique.
The mixed monolayer has been proved to be completely homogeneous.
Solar cooling has been proved to be technically feasible.
It has been proved to be non-deterministic polynomial hard.
This is an alternative energy source that has been proved to be safe and environmentally sound.
I'm pretty sure butter has been proved to be healthy now, hasn't it?
However, this has been proved to be a breach of the public trust".
Science fiction gave us grey goo and, fortunately, this has been proved to be overblown.
This method has been proved to be acceptable for systems with infinite conductivity hydraulic fractures.
The electrochemical reduction of CO2 (ERC) has been proved to be both technical and economic feasible.
Hydrogenation has been proved to be an efficient way to remove the toxicity of phthalate plasticizer.
Since I tried Ludwig back in 2017, I have been constantly using it in both editing and translation. Ever since, I suggest it to my translators at ProSciEditing.
Justyna Jupowicz-Kozak
CEO of Professional Science Editing for Scientists @ prosciediting.com