To tackle control channel saturation and triple hidden terminal problems, this paper proposes RIM, a receiver-initiated multi-channel MAC protocol with duty cycling for WSNs. By adopting a receiver-initiated transmission scheme and probability-based random channel selection, RIM effectively alleviates, if not completely eliminates, control channel saturation and triple hidden terminal problems. In addition, RIM exploits a simple but reliable asynchronous broadcast scheme to solve the problem of broadcast data loss with reliable broadcast-intensive applications. More importantly, RIM is fully distributed with no requirements of time synchronization or multi-radio. Therefore, RIM is very easily implemented in resource-constrained sensor nodes. Via the theoretical analysis, the optimal duty cycle are obtained, respectively. The simulation and real testbed experimental results show that RIM achieves significant improvement in energy efficiency with increasing benefit when the number of channels and traffic loads increase, while maintaining higher throughput. Moreover, RIM exhibits a prominent ability to enhance its broadcast reliability.