Compact, mechanically robust, and cost-effective mid-infrared (MIR) light sources are key components in portable and field-deployable gas sensors. Capitalizing on an efficient energy transfer mechanism between Co2+ and Fe2+, we have demonstrated for the first time, to the best of our knowledge, that ultrabroadband 2.5-5.5 µm MIR emission can be achieved at room temperatures in chalcogenide (ChG) glasses that are pumped by a commercially available erbium-doped fiber amplifier emitting at 1.57 µm. These MIR-transparent ChG glass ceramics are embedded with Co2+/Fe2+ codoped ZnSe nanocrystals, and show sufficient MIR emission intensities and bandwidths to enable gas sensing for multiple target analytes such as butane and carbon dioxide. We also describe, to the best of our knowledge, the first observation of a unique "anomalous" increase in the MIR luminescence intensity as a function of temperature.