Polymeric Carbon Nitride Research Articles

Engineering g-C3N4 with CuAl-layered double hydroxide in 2D/2D heterostructures for visible-light water splitting

CuAl layered double hydroxide (LDH) and polymeric carbon nitride (g-C3N4, GCNN) were assembled to construct a set of novel 2D/2D CuAl-LDH/GCNN heterostructures. These materials were tested towards H2 and O2 generation from water splitting using visible-light irradiation. Compared to pristine materials, the heterostructures displayed strongly enhanced visible-light H2 evolution, dependent on the LDH content, which acts as a cocatalyst, replacing the benchmark Pt. The optimal LDH loading was achieved for 0.2CuAl-LDH/GCNN that exhibited an increased number of active sites and showed a trade-off between charge separation efficiency and light shading, resulting in a 32-fold increase in the amount of evolved H2 compared with GCNN. In addition, the 0.2CuAl-LDH/GCNN heterostructure generated 1.5 times more O2 than GCNN. The higher photocatalytic performance was due to efficient charge carriers’ separation at the heterojunction interface via an S-scheme (corroborated by work function, steady-state and time-resolved photoluminescence studies), enhanced utilisation of longer-wavelength photons (>460 nm) and higher surface area available for the catalytic reactions.

Shear Stress Triggers Ultrathin-Nanosheet Carbon Nitride Assembly for Photocatalytic H2O2 Production Coupled with Selective Alcohol Oxidation.

Coupled photocatalysis without cocatalysts can maximize the utilization of photons and atoms, which puts forward higher demands on photocatalysts. Polymeric carbon nitride (CN) has become the most promising photocatalyst, but still suffers from major drawbacks of insufficient catalytic sites and low quantum efficiency. Herein, we report a fluid shear stress-assisted molecular assembly to prepare ultrathin-nanosheet-assembled acanthosphere-like CN (ASCN) with nitrogen vacancy (Nv) and carbonyl modification. Shear stress breaks the stacking interactions between layers and cuts the stacked structure into ultrathin layers, which are further reassembled into acanthosphere bundles driven by "centrifugal force". Benefitted greatly from the ultrathin nature that provides more exposed active sites and improves charge carrier separation, ASCN-3 exhibits a 20-fold higher activity than the bulk counterpart toward oxygen reduction to H2O2 coupled with 4-methoxybenzyl alcohol (4-MBA) oxidation to anisaldehyde (AA), with significantly increased turnover frequency (TOF) values (TOF: 1.69 h-1 for H2O2 and 1.02 h-1 for AA). Significantly, ASCN-3 exhibits 95.8% conversion for 4-MBA oxidation with nearly 100% selectivity. High apparent quantum yields of 11.7% and 9.3% at 420 nm are achieved for H2O2 photosynthesis and 4-MBA oxidation. Mechanism studies suggest that carbonyl induces holes concentrated at the neighboring melem unit to directly oxidize the Cα-H bond of 4-MBA to produce carbon radicals, and Nv as oxygen adsorption active site traps electrons to form a superoxide radical that further combines with the shed protons into H2O2. This work presents a simple physical method to break the layered stack of CN for creating hierarchical assembly for coupled photocatalysis.

Modulating the photooxidation selectivity on graphitic carbon nitride by tuning edge functional groups

Selective photooxidation reactions offer a promising route for transformation of organic pollutants into high-value products under mild conditions. In this work, we demonstrate that the edge functional groups in polymer carbon nitride (PCN) were key to the selectivity of methyl mercaptan (CH3SH) photocatalytic oxidation. The amino-decorated PCN favors the oxidation of the -SH group of CH3SH to forming CH3SO3H with selectivity up to 84.0%, while cyanamide-enriched PCN prefers to breaking the -CH3 end of CH3SH and produce H2SO4 with selectivity of 82.0%. The totally difference in reaction sites is ascribed to the functional-group-modulated electronic structure of PCN, which determines activity of photoinduced carriers and the molecular oxygen activation pathway. The amino- and cyanamide-decorated PCN leads to preferential generation of 1O2 and·O2-, respectively. This study highlights the significant role of edge groups engineering in modulation of the excitonic effects in PCN and the resultant selectivity control during photocatalytic reaction.

Bridging engineering of polymeric carbon nitride for boosting photocatalytic CO2 reduction

The inherent electron localized heptazine structure of carbon nitride (CN) derived from intrinsic tertiary N (N3C) bridging structure makes the photogenerated charge separation rather difficult, which severely limits photocatalytic CO2 activity of CN. Therefore, modulation of N3C bridging structure of CN is highly desirable to enhance the charge separation efficiency of CN. Herein, we reported a novel thiophene-bridged CN (BTCN) with intramolecular donor-π-acceptor (D-π-A) systems synthesized by nucleophilic substitution and Schiff base reaction to improve the photogenerated charge separation efficiency. The experimental and density functional theory (DFT) results indicate that this BTCN exhibits a high π-electron delocalization range and enhanced photogenerated charge transfer efficiency, which mainly account for the enhanced photocatalytic activity. The optimal BTCN photocatalyst exhibits enhanced charge separation efficiency and higher photocatalytic CO2 reduction activity with a CO yield of 23.02 μmol·g−1·h−1, which was higher than those of CN and edge-modified CN (ETCN) counterpart. This work highlights the importance of regulation of π-electron delocalization for the design of highly active CN photocatalysts via the rational substitution of N3C bridging structure with π-spacer molecular linkages for photocatalytic CO2 reduction.

Integration of Single-Atom Catalyst with Z-Scheme Heterojunction for Cascade Charge Transfer Enabling Highly Efficient Piezo-Photocatalysis.

Piezo-assisted photocatalysis (namely, piezo-photocatalysis), which utilizes mechanical energy to modulate spatial and energy distribution of photogenerated charge carriers, presents a promising strategy for molecule activation and reactive oxygen species (ROS) generation toward applications such as environmental remediation. However, similarly to photocatalysis, piezo-photocatalysis also suffers from inferior charge separation and utilization efficiency. Herein, a Z-scheme heterojunction composed of single Ag atoms-anchored polymeric carbon nitride (Ag-PCN) and SnO2- x is developed for efficient charge carrier transfer/separation both within the catalyst and between the catalyst and surface oxygen molecules (O2 ). As revealed by charge dynamics analysis and theoretical simulations, the synergy between the single Ag atoms and the Z-scheme heterojunction initiates a cascade electron transfer from SnO2- x to Ag-PCN and then to O2 adsorbed on Ag. With ultrasound irradiation, the polarization field generated within the piezoelectric hybrid further accelerates charge transfer and regulates the O2 activation pathway. As a result, the Ag-PCN/SnO2- x catalyst efficiently activates O2 into ·O2 - , ·OH, and H2 O2 under co-excitation of visible light and ultrasound, which are consequently utilized to trigger aerobic degradation of refractory antibiotic pollutants. This work provides a promising strategy to maneuver charge transfer dynamics for efficient piezo-photocatalysis by integrating single-atom catalysts (SACs) with Z-scheme heterojunction.

Highly selective photocatalytic CO2 reduction and hydrogen evolution facilitated by oxidation induced nitrogen vacancies on g-C3N4

The introduction of nitrogen vacancies into polymeric carbon nitride (PCN) has been attested to be a reliable strategy to enhance photocatalytic performance. Nitrogen vacancies were considered as active sites to promote the adsorption of target molecules and capture photoexcited electrons to inhibit the recombination of charge pairs, accelerate photoinduced electrons to participate in photocatalytic reaction. In this paper, a series of PCN with rich nitrogen vacancies were prepared by etching of chromic acid solution. Sample 20KCSCN had the highest photocatalytic performance whose evolution efficiency of CO2 to CO and CH4 can reach 3.9 and 0.5 μmol·g−1·h−1, respectively. These evolution efficiencies are 2.9 and 4 times higher than that of the PCN. Meanwhile, 20KCSCN demonstrates high CO conversion selectivity and stability. The successful introduction of nitrogen vacancies not only increases the active sites of PCN surface, but also optimizes the optical structure, which dramatically boosts the separation of photoexcited charge pairs and the reduction capacity of photogenerated electrons. The enhancement mechanism for photocatalytic CO2 reduction performance of PCN was proposed. Besides, photocatalytic H2 evolution experiments were performed on all samples to confirm the universality of PCN photocatalytic activity enhancement etched by chromic acid solution. H2 evolution rate on 20KCSCN can reach 652 μmol·g−1·h−1, which is 1.6-fold higher than that on PCN (254 μmol·g−1·h−1) after 4 h irradiation under a 300 W Xe lamp. This work offers new venue for introducing nitrogen vacancies in PCN to regulate photoexcited charge pairs transfer. The photocatalytic enhancement of CO2 reduction could be used to alleviate the serious issue of excessive CO2 emission and energy crisis.

Enhancement of intramolecular charge transfer in carbon nitride by attaching 2,4,5-Trichlorophenoxyacetic acid as electron acceptor units

The photocatalytic activity of polymeric carbon nitride (CN) can still be improved by increasing the separation efficiency of photogenerated electron-hole pairs. Herein, we successfully anchored onto the framework of CN 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) as electron acceptor moiety through thermal copolymerization to assist photoinduced charge separation. The influence of chlorine groups as electron-withdrawing substituents made 2,4,5-T an electron-deficient molecule, able to act as shallow electron traps and favoring charge carrier separation respect to pristine CN. The energy levels introduced by 2,4,5-T effectively narrow the band gap in the 2,4,5-T-derivatized CN, leading to better light harvesting. The nanotube structure of CN-(2,4,5-T)0.25 induced larger specific surface area, providing larger number of active sites. As result, CN-(2,4,5-T)0.25 displayed an excellent photocatalytic H2 evolution of 1845 μmol g-1h−1, 10.2 fold higher than that of CN. The methodology reported herein for the preparation of CN-(2,4,5-T) can be expanded to the rational design of efficient advanced CN nanomaterials exhibiting improved photocatalytic hydrogen production.

Bottom-up Synthesis of Single-Crystalline Poly (Triazine Imide) Nanosheets for Photocatalytic Overall Water Splitting.

Poly (triazine imide) (PTI/Li+Cl-), one of the crystalline versions of polymeric carbon nitrides, holds great promise for photocatalytic overall water splitting. In principle, the photocatalytic activity of PTI/Li+Cl- is closely related to the morphology, which could be reasonably tailored by the modulation of the polycondensation process. Herein, we demonstrate that the hexagonal prisms of PTI/Li+Cl- could be converted to hexagonal nanosheets by adjusting the binary eutectic salts from LiCl/KCl or NaCl/LiCl to ternary LiCl/KCl/NaCl. Results reveal that the extension of in-plane conjugation is preferred, when the polymerisation was performed in the presence of ternary eutectic salts. The hexagonal nanosheets bears longer lifetimes of charge carriers than that of hexagonal prisms due to lower intensity of structure defects and shorter hopping distance of charge carriers along the stacking direction of triazine nanosheets. The optimized hexagonal nanosheets exhibits a record apparent quantum yield value of 25% (λ=365nm) for solar hydrogen production by one-step excitation overall water splitting.

Bottom‐up Synthesis of Single‐Crystalline Poly (Triazine Imide) Nanosheets for Photocatalytic Overall Water Splitting

AbstractPoly (triazine imide) (PTI/Li+Cl−), one of the crystalline versions of polymeric carbon nitrides, holds great promise for photocatalytic overall water splitting. In principle, the photocatalytic activity of PTI/Li+Cl− is closely related to the morphology, which could be reasonably tailored by the modulation of the polycondensation process. Herein, we demonstrate that the hexagonal prisms of PTI/Li+Cl− could be converted to hexagonal nanosheets by adjusting the binary eutectic salts from LiCl/KCl or NaCl/LiCl to ternary LiCl/KCl/NaCl. Results reveal that the extension of in‐plane conjugation is preferred, when the polymerisation was performed in the presence of ternary eutectic salts. The hexagonal nanosheets bears longer lifetimes of charge carriers than that of hexagonal prisms due to lower intensity of structure defects and shorter hopping distance of charge carriers along the stacking direction of triazine nanosheets. The optimized hexagonal nanosheets exhibits a record apparent quantum yield value of 25 % (λ=365 nm) for solar hydrogen production by one‐step excitation overall water splitting.

Disulfide bond cross-linked three-dimensional graphitic carbon nitride nanocomposites with glutathione responsive fluorescence for cancer-cell specific bioimaging

The polymeric graphitic carbon nitride (g-C3N4) nanomaterials with non-toxicity, high stability, and photoluminescence property have promising application in bioimaging and biosensing. In this work, smart three-dimensional (3D) disulfide bond cross-linked g-C3N4 (CL-g-C3N4) nanocomposites with glutathione (GSH)-responsive fluorescence property were designed and developed for cancer cell-specific imaging. The g-C3N4 layered nanosheets with an average lateral size of 80–120 nm and mean thickness of ca. 0.5–1.0 nm were fabricated and used as building blocks. By combining several g-C3N4 nanosheets with non-fluorescent redox-sensitive disulfide bond-contained cross-linker, CL-g-C3N4 nanocomposites with a hydrodynamic particle size of ca. 270.5 nm were synthesized. The fluorescence of the CL-g-C3N4 nanocomposites was initially quenched due to the assembly of 2D g-C3N4 nanosheets into 3D structured nanocomposite caused by the crosslinking process. However, upon stirring them in a GSH solution with a concentration of 2 mM, which simulates the content in the cytoplasm of cells, the fluorescence was recovered to 89.3 % of its original intensity. This recovery was achieved through a thiol-disulfide exchange reaction, highlighting the GSH-responsive fluorescence recovery property of the nanocomposites. The cellular uptake traced images of CL-g-C3N4 in human cervix carcinoma (HeLa) cancer cells exhibited almost 3.5 times higher fluorescence intensity than that in human embryonic kidney (HEK 293 T) healthy cells owing to higher GSH concentration in cancer cells than that in healthy cells. The constructed CL-g-C3N4 nanocomposites should hold great promise as a fluorescence detector of cancer cells for early cancer diagnose.

Synthesis of nitrogen vacancy-riched ultrathin polymeric carbon nitride nanosheets via ethanol-ethylene glycol ultrasonic exfoliation and photocatalytic hydrogen evolution activity

Understanding the effects of active sites on photocatalyst surface is highly crucial in photocatalytic water-splitting hydrogen evolution. Herein, an exfoliated carbon nitride nanosheet (CNN) in two atomic layers with surface nitrogen vacancies (VNs) was used to investigate the correlation between VNs and photocatalytic hydrogen evolution activity. The few-layered CNNs were prepared via the exfoliation of block polymerized carbon nitride (PCN) with melon as the structural unit. The exfoliation was performed through an ultrasonication method assisted with ethanol and ethylene glycol mixture as the intercalation reagent. The results revealed that the formation of VNs on the peeled CNNs, accompanied with the increased content of hydroxyl. The effects of VNs on the electronic property of CNN and the water molecule adsorption are verified by the experimental results and DFT simulations. More interestingly, the photocatalytic hydrogen evolution activity of CNN was 2.14 times higher than that of PCN, which can be due to the successful introduction of VNs. This work may offer a novel insight into the effects of VNs of carbon nitride on photocatalytic hydrogen evolution.

Gram-scale synthesis of atomically dispersed p-block Al atoms on polymeric carbon nitride for efficient antibiotic photodegradation

Single-atom decorating polymeric carbon nitride (PCN) is often regarded as a class of promising catalyst for energy conversion and environmental remediation due to its ultrahigh atom utilization and unparalleled performance. Herein, gram-scale atomically dispersed p-block aluminum (Al) atoms on PCN photocatalyst (denoted as ACN) was successfully synthesized via a facile thermal polymerization strategy. Atomic-level, optical characterizations and band structure analysis unveil that Al atoms are uniformly dispersed on PCN framework, which can effectively optimize the band structure, accelerate the separation and transport ability of carriers, and then facilitate antibiotics photodegradation efficiency. Remarkably, the optimal ACN-2 exhibits superb removal rates (∼80%) and outstanding pseudo-first-order kinetic constants (0.084 min−1, 0.051 min−1 and 0.067 min−1, respectively) over visible-light-induced degradation of tetracycline, oxytetracycline and chlortetracycline in just 20 min, and ca. 95% of the original removal rate can be maintained even in 10 consecutive TC degradation cycles, illustrating the superior stability and reusability of ACN-2. Notably, >30 g of photocatalyst (i.e., ACN-500) obtained via precursor amplification procedure still displayed excellent TC photodegradation performance. This work paves the way for practical application of an advanced single-atom Al-decorated PCN photocatalyst for pollutant remediation.

Enhanced photocatalytic H2 production independent of exciton dissociation in crystalline carbon nitride

The role of exciton dissociation in charge separation dominated by in-plane crystallinity has been rarely addressed, although it is the decisive step of polymeric carbon nitride (CN) photocatalysis. Here, taking ten kinds of crystalline carbon nitride (CCN) as examples, the relationship between exciton dissociation, carrier mobility, conductivity, charge separation and photocatalytic activity under different in-plane crystallinity has been investigated. Although the in-plane crystallinity dominates charge separation and photocatalytic activity, it does not significantly reduce excitons binding energy (EBE) or improve exciton dissociation efficiency (EDE), only decreasing by 1.5 meV and increasing by 2.3 %, respectively. It is the greatly improved carrier mobility and conductivity that are more responsible for the increased charge separation and photocatalytic activity than the slight change in EDE. To our knowledge, this is the first reported case of overall water splitting in CCN of poly(heptazine imide) structure, resulting from the optimized in-plane crystallinity.

Molecular engineering of carbon nitrides for overall photosynthesis of H2O2

Artificial photocatalysis offers a promising strategy to sustainably produce hydrogen peroxide (H2O2) that is one of the most valuable multifunctional chemicals. Among various photocatalysts, polymeric carbon nitride (pCN) has drawn continuous attention in non-sacrificial H2O2 production. However, the poor activity of half reactions, i.e., the oxygen reduction reaction (ORR) and water oxidation reaction (WOR), greatly restricts the efficiency of photocatalytic H2O2 production. In this highlight, we discuss the significant advances in molecular engineering of carbon nitrides for H2O2 photosynthesis and the importance of the deep understanding of the photocatalysis process for rational design and reaction pathways of organic conjugated polymers to address the growing H2O2 demand. Furthermore, we summarize the emerging applications of photocatalytic H2O2 productions beyond energy and environment.

Regulation of Polymerization Kinetics to Improve Crystallinity of Carbon Nitride for Photocatalytic Reactions.

Carbon nitride (CN) polymers exhibit tunable and fascinating physicochemical properties and are thus an essential class of photocatalytic materials with potential applications. Although significant progress has been made in the fabrication of CN, the preparation of metal-free crystalline CN via a straightforward method remains a considerable challenge. Herein, we describe a new attempt to synthesize crystalline carbon nitride (CCN) with a well-developed structure through regulation of the polymerization kinetics. The synthetic process involves the pre-polymerization of melamine to remove most of the ammonia and further calcination of the pre-heated melamine in the presence of copper oxide as an ammonia absorbent. Copper oxide can decompose the ammonia produced by the polymerization process, thereby promoting the reaction. These conditions facilitate the polycondensation process while avoiding carbonization of the polymeric backbone at high temperatures. Owing to the high crystallinity, nanosheet structure, and efficient charge-carrier transmission capacity, the as-prepared CCN catalyst shows much higher photocatalytic activity than its counterparts. Our study provides a novel strategy for the rational design and synthesis of high-performance carbon nitride photocatalysts by simultaneously optimizing polymerization kinetics and crystallographic structures.

Ni-anchored g-C3N4 for improved hydrogen evolution in photocatalysis

In this study, we present a facile wet chemical method for synthesizing Ni-modified polymeric carbon nitride (g-C3N4) nanosheets. X-ray absorption fine structure spectroscopy reveals the formation of a unique Ni–N structure, resulting from Ni atoms anchoring in cavities of g-C3N4. The Ni anchoring on the surface N sites modifies the electronic structure of g-C3N4, demonstrating remarkable effectiveness even at low anchoring amounts. The as-prepared Ni/g-C3N4 catalysts show robust performance for photocatalytic hydrogen evolution under visible light irradiation, attributed to the unique Ni–N interactions. Specifically, the photocatalytic H2 production rate of the Ni/CN-45 catalyst reached 8482.14 μmol·g−1·h−1 with an apparent quantum efficiency of 0.75% under light irradiation at 427 nm. This rate surpasses most of the previously reported g-C3N4 based photocatalysts and is nearly 8 times higher than that of the pure g-C3N4 catalyst (1116.07 μmol·g−1·h−1).

Interfacial Affinity Determined Photocatalytic Activity: A Comparison between Defective and Bulk Polymeric Carbon Nitride.

The photoexcited charge separation efficiency of photocatalysts is generally considered as the key factor for enhancement of their photocatalytic activity, and sometimes, their photoabsorption capability and interfacial reaction kinetics play a key part, but the role of interfacial affinity of photocatalysts with substrates was rarely researched systematically. Herein, nitrogen vacancy-modified polymeric carbon nitride porous nanotubes (PCNpts) were simply synthesized, using tartaric acid as a crosslinking and corrosion agent, and exhibit a remarkable increment in surface area, wettability, photoabsorption and charge separation capability, and photocatalytic activity in water splitting to produce H2, but, interestingly, exhibit substrate-dependent variation of photoactivity in contaminant degradation, compared with bulk PCN. More interestingly, the interfacial affinity of PCNpts and PCN with contaminants and H2O, rather than photoabsorption and charge separation capability, is confirmed to dominate their photoactivity.

Fabrication of copper molybdate nanoflower combined polymeric graphitic carbon nitride heterojunction for water depollution: Synergistic photocatalytic performance and mechanism insight

In the scope, developed a novel copper molybdate decorated polymeric graphitic carbon nitride (CuMoO4@g-C3N4 or CMC) heterojunction nanocomposite in an easy solvothermal environment for the first time. The synthesized CMC improved the photocatalytic degradation of an antibiotic drug [ciprofloxacin (CIP)] and organic dye [Rhodamine B (RhB)]. Consequently, the CMC demonstrates a marvelous crystalline nature with ∼26 nm size, as obtained from XRD analysis. Besides, the surface morphology studies confirm the large-scale construction of flower-like CMC with a typical size of 10–15 nm. The CMC showed efficient catalytic activity for both the pollutants, achieving the degradation of 98% for RhB and 97% for CIP in 35 and 60 min, respectively. The reaction parameters including the concentration of pollutants, catalyst dosages, and scavengers are optimized for the best photocatalytic results. Notably, the trapping tests showed that the •OH and O2•− radicals are the primary oxidative species liable for the photocatalytic process. The recyclability test of the photocatalyst infers that the photocatalyst is highly stable up to the fifth recycle. Our work affords an efficient and ideal path to constructing the new g-C3N4-based architected photocatalyst for toxic wastewater treatment in the near future.

Boron and Sodium Doping of Polymeric Carbon Nitride Photoanodes for Photoelectrochemical Water Splitting.

Polymeric carbon nitride is a promising photoanode material for water-splitting and organic transformation-based photochemical cells. Despite achieving significant progress in performance, these materials still exhibit low photoactivity compared to inorganic photoanodic materials because of a moderate visible light response, poor charge separation, and slow oxidation kinetics. Here, the synthesis of a sodium- and boron-doped carbon nitride layer with excellent activity as a photoanode in a water-splitting photoelectrochemical cell is reported. The new synthesis consists of the direct growth of carbon nitride (CN) monomers from a hot precursor solution, enabling control over the monomer-to-dopant ratio, thus determining the final CN properties. The introduction of Na and B as dopants results in a dense CN layer with a packed morphology, better charge separation thanks to the in situ formation of an electron density gradient, and an extended visible light response up to 550nm. The optimized photoanode exhibits state-of-the-art performance: photocurrent densities with and without a hole scavenger of about 1.5 and 0.9mA cm-2 at 1.23V versus reversible hydrogen electrode (RHE), and maximal external quantum efficiencies of 56% and 24%, respectively, alongside an onset potential of 0.3V.

Bifunctional Hot Water Vapor Template-Mediated Synthesis of Nanostructured Polymeric Carbon Nitride for Efficient Hydrogen Evolution.

Regulating bulk polymeric carbon nitride (PCN) into nanostructured PCN has long been proven effective in enhancing its photocatalytic activity. However, simplifying the synthesis of nanostructured PCN remains a considerable challenge and has drawn widespread attention. This work reported the one-step green and sustainable synthesis of nanostructured PCN in the direct thermal polymerization of the guanidine thiocyanate precursor via the judicious introduction of hot water vapor's dual function as gas-bubble templates along with a green etching reagent. By optimizing the temperature of the water vapor and polymerization reaction time, the as-prepared nanostructured PCN exhibited a highly boosted visible-light-driven photocatalytic hydrogen evolution activity. The highest H2 evolution rate achieved was 4.81mmol∙g-1∙h-1, which is over four times larger than that of the bulk PCN (1.19 mmol∙g-1∙h-1) prepared only by thermal polymerization of the guanidine thiocyanate precursor without the assistance of bifunctional hot water vapor. The enhanced photocatalytic activity might be attributed to the enlarged BET specific surface area, increased active site quantity, and highly accelerated photo-excited charge-carrier transfer and separation. Moreover, the sustainability of this environmentally friendly hot water vapor dual-function mediated method was also shown to be versatile in preparing other nanostructured PCN photocatalysts derived from other precursors such as dicyandiamide and melamine. This work is expected to provide a novel pathway for exploring the rational design of nanostructured PCN for highly efficient solar energy conversion.