I've noticed that making a positional pawn sacrifice with the black pieces is becoming popular at the highest level. The sacrifice is not made in order to attack, but in order to simplify the position and draw the game. This type of pawn sacrifice can take place in mainstream openings including the Catalan, Sicilian and Tarrasch.
The advantages of playing this way are as follows:
These lines are relatively easy to play and learn. The centre tends to open up early and then its a matter of playing natural active piece moves.
By playing this way, you take control of the opening direction early on, instead of giving the opponent a chance to unleash a surprise of their own.
You know that whatever happens, your opponent will not win easily. They will have to hang on to their extra pawn, neutralize all the activity and pressure, and then find a way to win a slightly better endgame.
The main disadvantage is that it is difficult to play for a win because white can usually just give the pawn back in order to relive the pressure.
Catalan
Lets start with the main line of the Catalan opening.
https://lichess.org/X3LBYHaK#18
This line is a favourite of Nakamura. Black sacrifices a pawn on b5, in exchange for piece activity. Usually, the game ends in a draw. Black either uses the piece activity to win the pawn back, or simplifies to a drawn endgame, such as a pawn down endgame with opposite colour bishops.
Sicilian
The 4 knights variation of the Sicilian defence has two main lines. White can either go for 6.Nxc6 followed by e5, or play 6.Ndb5. After 6.Nbd5, most players play 6...d6 and transpose to the complicated Sveshnikov variation.
The move 6...Bb4 has not been popular due to white getting the bishop pair while black gets an isolated pawn. However, a new pawn sacrifice has been discovered in this line, with move 14...Ne4 that gives black a simple and nearly forced path to an endgame with good drawing chances.
https://lichess.org/BVqtgqt5#28
The opposite coloured bishops give black good drawing chances.
Tarrasch
This pawn sacrifice line of the Tarrasch has not been taken seriously by top players for a long time. It was treated like a gambit opening in which black castles queenside and tries to pawn-storm the white king.
Recently, Carlsen has been using this sacrifice to get long term positional compensation, without trying to checkmate the opponent straight away.
