Crate training is an important skill for your dog to learn, especially until he can be trusted not to chew up furniture or have accidents in the house. However, you can't leave a dog in his crate for longer than 4 to 6 hours, even less for puppies, so you should have an alternative in mind if you work all day.
X-Pen
X-pens are small wire pens that can contain your dog in a small area while providing more freedom than a crate. You can make these areas large enough to add a bed, a few toys or treats and a potty pad if your dog isn't house trained yet.
Since your dog is not so confined, he can move with a little more freedom and won't get as cramped as a dog in an airline crate that only has enough room to stand up and turn around. Your dog can also see more of your house, which feels less conflicting. Though your dog still doesn't have enough room to run and play, it's not as confining as a crate.
However, it serves the same purpose as a crate because you can place it in a room where there are no rugs or carpeting for accidents and far enough away from furniture that your untrained dog can't chew up anything he's not supposed to. This is a great option for a young puppy.
Bathroom
If you are going to be gone long periods of time and want your dog to have more freedom than the crate, consider placing them in a small room like the bathroom or laundry room. These rooms often have tile floors so accidents are easy to clean. It also make potty pads more appealing because dogs usually don't like to pee on tile.
These rooms often also smell like you. There may be clothes in the room or rugs that may carry your scent, making your dog feel more comfortable in your absence. Place a bed on the floor and pick up any objects that your dog might chew. Your dog can still chew walls, molding or flooring in these rooms, but it's safer than giving him run of the house.
Baby Gates
As your dog gets older, he may only need minor restrictions or may have earned the right to be in a larger room, like a kitchen or living area. Baby gates are a great way to ensure your dog won't get into trouble in some of the nicer rooms in your house while allowing him more freedom.
You can also use baby gates rather than closing doors to keep your dog in his small room, such as the bathroom, so he doesn't feel quite so confined.
Start by baby gating your dog in a small room, such as the kitchen and then gradually build up the amount of rooms in which your dog is allowed. If he chews something up or has an accident, just go back to baby gating him in the last place where he was successful. Start to build up again in a few weeks. Eventually, maybe your dog will have access to most of the house, once he can be trusted to behave.