Yes there are more than one method etching is one of them

For Ceramic oxide, better to go for "plasma etching" which can created nano grooves throughout the surface and also further can increase the surface area to capture more light.

Thank you so much for valuable comments.

dear Muhammad Sultan Irshad;

the concentration of electrochemical solution effect on the surface characteristics, in my research I found that the increasing of oxalate concentration increases solution conductivity leading to form a coating of larger grain size with fewer pores. and the decreases of temperature decrease coating porosity. more details in this reference;

Article Influence of oxalate concentration and temperature on the mi...