Iron-chromium redox flow battery (ICRFB) is an electrochemical energy storage technology that plays a vital role in dealing with the problems of discontinuity and instability of massive new energy generation and improving the acceptance capacity of the power grid. Carbon cloth electrode (CC) is the main site where the electrochemical reaction occurs, which always suffers from the disadvantages of poor electrochemical reactivity. A new N-B co-doped co-regulation Ti composite CC electrode (T-B-CC) is firstly generated and applied to ICRFB, where the REDOX reaction can be promoted significantly owing to the plentiful active sites generated on the modified electrode. As contrasted with ICRFB with normal CC electrode, after 50 battery charge/discharge cycles, the discharge capacity (1,990.3 ​mAh vs 1,155.8 ​mAh) and electrolyte utilization (61.88% vs 35.94%) of ICRFB with CC electrode (T-B-CC) are significantly improved. Furthermore, the energy efficiency (EE) is maintained at about 82.7% under 50 cycles, which is 9.3% higher than that of the pristine electrically assembled cells. The co-modulation of heteroatom doping and the introduction of Ti catalysts is a simple and easy method to improve the dynamics of the Cr³⁺/Cr²⁺ and Fe³⁺/Fe²⁺ reactions, enhancing the performance of ICRFBs.

The in situ mining technology is applied to the exploitation of medium- and low-maturity shale oil, which can use heaters to warm up the oil shale formations and pyrolyze the kerogen. Due to the low thermal conductivity of oil shale, electric heaters need extra equipment to improve heat transfer efficiency. In this study, a thermally conductive proppant is fabricated by coating epoxy-resin and graphite on ceramic proppants for the first time, which could support the fracturing crack and transfer heat. The thermal conduction property of epoxy-resin and graphite coated proppants (EGPs) is 245% higher than that of uncoated proppants, which can transfer more heat to the oil shale formation and accelerate the conversion of kerogen. The adhesive property of EGPs is improved by 47.9% under the load force of 1500 nN, which prolongs the time for the fracture to close. In summary, this novel proppant is expected to assist in-situ mining technology in the production of medium and low-maturity shale oil.

Despite enormous efforts in actuators, most researches are only limited to various actuation behaviors and demonstrations of soft materials. It has not yet been reported to capture and monitor its movement status in an invisible environment. Therefore, it is of great significance to develop a self-sensing and self-actuating dual-function hydrogel actuator system to realize real-time monitoring. Here, we report a bifunctional hydrogel system with self-actuating and self-monitoring abilities, which combines the functions of photothermal actuation and electrical resistance sensing into a single material. The bilayer tough conductive hydrogel synthesized by unconventional complementary concentration recombination and cryogenic freezing technique presents a dense conductive network and high-porosity structure, achieving high toughness at 190.3 kPa of tensile strength, high stretchability (164.3% strain), and the toughness dramatically (1,471.4 kJ·m⁻³). The working mechanism of the monitoring and self-sensing system is accomplished through the integrated monitoring device of surface temperature–bending angle–electron current, to solve the problem of not apperceiving actuator motion state when encountering obstacles in an invisible environment. We demonstrated for the first time a photothermal actuator’s motion of a football player and goalkeeper to finish the penalty and a soft actuator hand, which can achieve the action of sticking to grab and release under photo-thermal actuation. When connected to the control closed circuit, the actuator realized closed-loop monitoring and sensing feedback. The development of bifunctional hydrogel systems may bring new opportunities and ideas in the fields of material science, circuit technology, sensors, and mechanical engineering.