To expand further, lowering interest rates at the ZLB doesn't do anything because people will hold money rather than deposit it at a nominal interest rate at or

To expand further, lowering interest rates at the ZLB doesn't do anything because people will hold money rather than deposit it at a nominal interest rate at or below zero. Hence, central banks must buy assets: treasuries in the case of the Fed and JGB/ETFs in the case of BoJ. Buying assets is effective at the ZLB, according to Keynesians anyhow.