An advanced supercapacitor material based on nitrogen-doped porous graphitic carbon (NPGC) with high a surface area was synthesized by means of a simple coordination-pyrolysis combination process, in which tetraethyl orthosilicate (TEOS), nickel nitrate, and glucose were adopted as porogent, graphitic catalyst precursor, and carbon source, respectively. In addition, melamine was selected as a nitrogen source owing to its nitrogen-enriched structure and the strong interaction between the amine groups and the glucose unit. A low-temperature treatment resulted in the formation of a NPGC precursor by combination of the catalytic precursor, hydrolyzed TEOS, and the melamine-glucose unit. Following pyrolysis and removal of the catalyst and porogent, the NPGC material showed excellent electrical conductivity owing to its high crystallinity, a large Brunauer-Emmett-Teller surface area (SBET =1027 m(2)  g(-1) ), and a high nitrogen level (7.72 wt %). The unusual microstructure of NPGC materials could provide electrochemical energy storage. The NPGC material, without the need for any conductive additives, showed excellent capacitive behavior (293 F g(-1) at 1 A g(-1) ), long-term cycling stability, and high coulombic efficiency (>99.9 % over 5000 cycles) in KOH when used as an electrode. Notably, in a two-electrode symmetric supercapacitor, NPGC energy densities as high as 8.1 and 47.5 Wh kg(-1) , at a high power density (10.5 kW kg(-1) ), were achieved in 6 M KOH and 1 M Et4 NBF4 -PC electrolytes, respectively. Thus, the synthesized NPGC material could be a highly promising electrode material for advanced supercapacitors and other conversion devices.

An easily accessible photocathodic material was fabricated to realize high-efficiency water splitting. After optimizing the PEC system, the photocurrent was further amplified to −1.2 mA cm−2.

The monolithic integration of solar energy conversion and electrochemical energy storage offers a practical solution to provide uninterruptable power supply on demand regardless of the ebb and flow of solar irradiation. Although connecting photovoltaics (PVs) with batteries, as adopted by some solar farms nowadays, [1] can provide the same uninterrupted power supply, the high capital cost and large footprint of two separate devices limit the market cases feasible for this option. [2] In contrast, integrated solar energy conversion and storage may represent a more compact, efficient, and cost-effective approach for off-grid electrification. [3] Among the many different types of "solar rechargeable battery" devices that have been reported [3,4] since the first demonstration in 1976, [5] integrated solar flow batteries (SFBs) hold great promises for practical applications because the solar component shares the same liquid electrolyte as the energy storage component, [6] which is based on redox flow batteries (RFBs) and can be easily scaled up. [2b] Despite the significant progress, most of such integrated devices suffer from some common scientific and technical issues. [4a,7] The first question one typically asks about any "solar device" is the efficiency. Due to the intrinsic efficiency limits of the solar energy conversion components and the working voltage mismatch between the solar energy conversion component and electrochemical energy storage component, the round-trip efficiency (i.e., solar-to-output electricity efficiency, SOEE) of most previously reported solar rechargeable devices rarely exceeded 5%. [3a,4a,7,8] It was recently demonstrated that by monolithically integrating III-V tandem junction solar cells with properly voltage matched RFBs, the integrated SFB device can deliver a SOEE of 14.1%. [9] Importantly, this comprehensive study [9] also revealed a set of general design principles that can further boost the SFB's efficiency. Primary among them is that the formal potential difference of selected redox couples needs to be closely matched with the photovoltage of the photoelectrodes at the maximum power point. Although III-V tandem junction solar cells can enable unprecedented high SOEE, the manufacturing cost for them ($40 W −1 to over $100 W −1 ) [10] is too high for practical applications. The most widely produced crystalline silicon-based solar cells have the cost of $0.15 to $0.25 W −1 after decades of research and commercial deployment, [10] thus are a good candidate for practical SFBs owing to its high abundance and decent PV efficiency.Monolithically integrated solar flow batteries (SFBs) hold promise as compact stand-alone energy systems for off-grid solar electrification. Although considerable research is devoted to studying and improving the round-trip efficiency of SFBs, little attention is paid to the device lifetime. Herein, a neutral pH aqueous electrolyte SFB with robust organic redox couples and inexpensive silicon-based photoelectrodes is demonstrated. Enabled by the excellent ...