Highly active, low pressure drop catalyst systems. Catalytically active material is provided on at least a portion of the channel sidewalls of a body comprising one or more flow-through channels. The channel sidewalls preferably bear a charge, e.g., an electrostatic or electret charge, to help adhere the catalytically active material to the sidewall. The catalytically active material preferably includes gold provided on a particulate support, and PVD techniques are used to deposit catalytically active gold onto the support. Optionally, the gold-bearing particulates may be charged as well in a manner to facilitate attraction between the particulates and the sidewalls.